Title: Curiosities of Heat
Author: Tefft, Lyman B.
Language: English
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[Illustration: EFFECT of HEAT.

Frontispiece.]


CURIOSITIES OF HEAT.

by

REV. LYMAN B. TEFFT.



Philadelphia:
The Bible and Publication Society,
530 Arch Street.

Entered according to Act of Congress, in the year 1871, by
The Bible and Publication Society,
In the office of the Librarian of Congress, at Washington.

Westcott & Thomson,
Stereotypers, Philada.



CONTENTS.


                                              PAGE

  CHAPTER I.

    MR. WILTON'S BIBLE CLASS                     7

  CHAPTER II.

    NEW THOUGHTS FOR THE SCHOLARS               26

  CHAPTER III.

    A DIFFICULT QUESTION                        58

  CHAPTER IV.

    HEAT A GIFT OF GOD                          83

  CHAPTER V.

    CONVEYANCE AND VARIETIES OF HEAT           100

  CHAPTER VI.

    MANAGEMENT AND SOURCES OF HEAT             120

  CHAPTER VII.

    PRESERVATION AND DISTRIBUTION OF HEAT      152

  CHAPTER VIII.

    MODIFICATION OF TEMPERATURE                176

  CHAPTER IX.

    THE MINISTRY OF SUFFERING                  190

  CHAPTER X.

    TRANSPORTATION OF HEAT                     213

  CHAPTER XI.

    AN EFFECTIVE SERMON                        233

  CHAPTER XII.

    TRANSFER OF HEAT IN SPACE                  254

  CHAPTER XIII.

    OCEAN CURRENTS AND ICEBERGS                272

  CHAPTER XIV.

    COMBUSTION.--COAL-BEDS                     292

  CHAPTER XV.

    ECONOMY OF HEAT                            305

  CHAPTER XVI.

    A DAY OF JOY AND GLADNESS                  320



CURIOSITIES OF HEAT.



CHAPTER I.

MR. WILTON'S BIBLE CLASS.


"The book of Nature is my Bible. I agree with old Cicero: I count Nature
the best guide, and follow her as if she were a god, and wish for no
other."

These were the words of Mr. Hume, an infidel, spoken in the village store.
It was Monday evening. By some strange freak, or led by a divine impulse,
he had determined, the previous Sunday afternoon, to go to church and hear
what the minister had to say. So the Christian people were all surprised
to see Mr. Hume walk into their assembly--a thing which had not been seen
before in a twelvemonth. Mr. Hume did not shun the church from a dislike
of the minister. He believed Mr. Wilton to be a good man, and he knew him
to be kind and earnest, well instructed in every kind of knowledge and
mighty in the Scriptures. He kept aloof because he hated the Bible. He had
been instructed in the Scriptures when a boy, and many Bible truths still
clung to his memory which he would have been glad to banish. He could not
forget those stirring words which have come down to us from the Lord
Jesus, and from prophets and apostles, and they sorely troubled his
conscience. He counted the Bible an enemy, and determined that he would
not believe it.

At that time there was an increasing religious interest in the church. Mr.
Wilton had seen many an eye grow tearful as he unfolded the love of Christ
and urged upon his hearers the claims of the exalted Redeemer. He found an
increasing readiness to listen when he talked with the young people of his
congregation. The prayer-meetings were filling up, and becoming more
interesting and solemn. The impenitent dropped in to these meetings more
frequently than was their wont. Mr. Wilton himself felt the power of
Christ coming upon him and girding him as if for some great spiritual
conflict. His heart was filled with an unspeakable yearning to see
sinners converted and Christ glorified. He seemed to himself to work
without fatigue. His sermons came to him as if by inspiration of the Holy
Spirit. He felt a new sense of his call from God to preach the gospel to
men, and spoke as an ambassador of Christ, praying men tenderly,
persuadingly, to be reconciled to God, yet as one that has a right to
speak, and the authority to announce to man the conditions of salvation.

A few of the spiritual-minded saw this little cloud rising, but the people
in general knew nothing of it. Least of all did Mr. Hume suspect such an
undercurrent of religious interest; yet for some reason, he hardly knew
what, he felt inclined to go to church.

That afternoon the preacher spoke as if his soul were awed, yet lifted to
heavenly heights, by the presence of God and Christ. Reading as his text
the words, "Thou thoughtest that I was altogether such an one as thyself"
(Ps. l. 21), he showed, first, the false notions which men form of God,
and then unfolded, with great power and pungency, the Scripture revelation
of the one infinite, personal, living, holy, just, and gracious Jehovah.
This was the very theme which Mr. Hume wished most of all not to hear.
That very name, Jehovah, of all the names applied to God, was most
disagreeable; it suggested the idea of the living God who manifested
himself in olden time and wrought wonders before the eyes of men. But the
infidel, with his active mind, could not help listening, nor could he
loosen his conscience from the grasp of the truth. Yet he could fight
against it, and this he did, determined that he would not believe in such
a God--a God who held him accountable, and would bring him into judgment
in the last great day. In this state of mind he dropped into Deacon
Gregory's store.

Deacon Gregory was accustomed to obey Paul's injunction to Timothy: "Be
instant in season, out of season; reprove, rebuke, exhort with all long
suffering and doctrine." Having taken Mr. Hume's orders for groceries, he
said, "I was glad to see you at church yesterday, Mr. Hume. How were you
interested in the sermon?"

"I like Mr. Wilton," answered Mr. Hume; "I think him a very earnest and
good man."

"But were you not interested and pleased with the discourse? It seems to
me that I shall never lose the impression of God's existence and
character which that discourse made upon me. I almost felt that Mr. Wilton
spoke from inspiration."

"I suppose he was inspired just as much as the writers of that book which
men call 'the Bible.'"

"But can you wholly get rid of the conviction that the Bible is the word
of God, written by holy men inspired by the Holy Spirit?"

"You know, Deacon Gregory, that I do not believe what you profess to
believe. The book of Nature is my Bible. I agree with old Cicero: I count
Nature the best guide, and follow her as if she were a god, and wish no
other."

Deacon Gregory had never read Cicero, and of course did not attempt to
show, as he might otherwise have done, that Cicero did not mean to deny
the existence of a living, personal God, who governs the world.

"But," said he, "does not the book of Nature--your Bible, as you call
it--have something to say of God? Does it not speak of an infinitely wise
and good Creator and Governor? Do not the works of Nature tell of the same
God whose being and character were preached to us yesterday from the Holy
Scriptures?"

"Nature has never spoken to me of any God except herself. What need is
there of a creator? Who can prove that the universe did not exist from
eternity? Nature has her laws of development, and under those laws all the
operations of nature go on. You had better read Darwin. If one must find
the character of God in nature, he may as well picture an evil creator and
governor as one that is good and righteous. Does Nature punish those whom
you call the wicked? Does Nature reward the righteous? Do not the laws of
Nature bring suffering to the good and the bad alike, and happiness also
to all classes of men? Would you, if you had power, create a world like
this--a world in which danger, pain, and death, in every shape, lie in
ambush against its inhabitants every hour of their poor existence? But I
must go." Pausing a moment, however, as if reluctant to go, with a voice
sad and almost tremulous, which revealed a great deal more of his heart
than he designed to express, he added: "God knows, deacon, if there be a
God, how I wish I knew the truth about these matters. The world and myself
are to me great and dreadful mysteries."

"'He that will do his will shall know of the doctrine,'" answered Deacon
Gregory; and inviting him to come to church again, they separated.

This conversation with the pious deacon, though he had himself done most
of the talking and had his say almost unopposed, did not tend at all to
bring rest to Mr. Hume's conscience. He saw that the deacon's faith in God
did for him more than belief in Nature and worship at the altar of Science
could do for unbelievers. He felt also that he had spoken a little too
freely, especially in revealing, at the last, his unrest of spirit from
the want of fixed convictions in regard to religious truth. Deacon
Gregory, by the sincerity and manliness of his address, was accustomed to
draw out the hearts of men so that they expressed them more freely than
they designed.

Upon a bench in a shaded corner of the store sat a lad of sixteen or
seventeen years, unnoticed for the time being by either Mr. Hume or Deacon
Gregory. His name was Ansel, and he was the son of the senior deacon of
the church. He was in the village academy, and had there been nearly
fitted for college. He stood at the head of his class, and, with his sharp
intelligence, his impetuous energy, and high ambition, every one was
predicting for him a distinguished life. He had grown up thus far in the
bosom of a family where piety was no pretence. Earnest prayer had gone up
for him by day and by night. He had been well trained in the
Sunday-school, and for a year had been a member of the small class of
young men taught by Mr. Wilton. He had always shown a ready interest in
all Bible studies and a quick understanding of Scripture doctrine, so that
some thought him not far from the kingdom of God. But Deacon Arnold little
thought what was in the heart of his son. He might have known, for to
read his son's heart he had only to recall his own early manhood. For
years he had hung trembling upon the brink of ruin, swept, at times,
by his self-will and turbulent youthful passions, to the very verge
of the precipice, and had been preserved only by singular grace
from falling over. Now Ansel was following in his father's early
footsteps--self-willed, and stubborn against the Spirit of God, and, at
times, almost persuaded to cast off all religious restraint, that he might
carve out his worldly fortunes untrammeled by religious or conscientious
scruples. He had rarely heard infidel sentiments expressed, but the little
that he had heard had attracted him, and had encouraged him to give loose
reins to his own unbelieving disposition. It had not escaped his notice
that the two or three men whom he had heard spoken of as infidels were
among the most respectable and shrewdest business-men in the village. The
idea, moreover, of rejecting all authoritative doctrine, and believing
whatever should please him, carried with it so free and independent an
air, and harmonized so well with his natural disposition, that he easily
drifted in the direction of unbelief.

Sitting this evening unobserved, he drank in every word which Mr. Hume
uttered. Some of the notions thrown out were quite new to him. "The book
of Nature my Bible"--"Nature reveals no God but her own laws"--"No proof
that the matter of the universe has not existed from eternity
uncreated"--"Nature has her laws of development"--"No need of a God to
govern the world,"--these were seed-thoughts in Ansel's mind. He had
before thought of the only alternative to be set over against belief in
the sacred Scriptures as simply unbelief--bare, blank denial of their
truth. He had not dreamed of building up a set of proud, rationalistic
notions, and denying the truths of religion in the character of a young
philosopher. He kept his thoughts to himself, and turned them over and
over in his mind during the week, and when again he met his pastor in the
Bible class his head was full of his new notions. The lesson went on,
however, and closed as usual. It so happened that this was the last in a
series of lessons upon the Gospel of John. It was necessary, therefore,
that another course of lessons should be decided upon.

Mr. Wilton proposed the question to the class: "What shall be our next
course of lessons? Would you like to study one of the Epistles--the
Epistle to the Romans or that to the Hebrews?" And he briefly stated the
subject discussed in these Epistles of Paul. "Perhaps," he continued, "you
would prefer to study one of the historic books of the Old Testament?" The
class had no opinion. They wavered between an Epistle and a historic book
and topical lessons which should confine them to no one book of the Bible.
Then Ansel spoke up:

"Mr. Wilton, why can we not study something which we know to be true?"

Ansel meant to be very cautious as well as very respectful, and did not
design to commit himself by suggesting his own thoughts. He was
respectful, but in the confusion of the moment he had brought out the very
thoughts which he meant to conceal.

Mr. Wilton was startled, though he did not fully understand the drift of
Ansel's question.

"What do you mean, Ansel?" he asked; "do you think Genesis less
trustworthy than the Epistle of Paul?"

Ansel saw that he had committed himself and must now make the best of his
situation. He therefore answered cautiously:

"Some persons, I have heard said, do not believe the Bible to be inspired,
and they say that we have no evidence that it is true."

"What have you been reading, Ansel, that has put such thoughts into your
mind?"

"I have never read a book that said anything against the Bible."

"But what did you mean? Do you wish to study the evidences of the truth
and inspiration of the Holy Scriptures?"

"I should indeed like a course of lessons upon that subject, but that was
not quite what I was thinking of."

"What book can you find which is true if the Bible is not true?"

"I do not know, sir, but I heard Mr. Hume say that the book of Nature is
his Bible, and that we do not need any other, and that, whether the Bible
be true or not, we know that the teachings of Nature must be true."

"But we should find," said Mr. Wilton, "that the teachings of Nature and
the Bible would perfectly agree. Did Mr. Hume say that what he calls 'The
book of Nature' contradicts the sacred Scriptures?"

Now that Ansel could give the thoughts which filled his mind, not as his
own, but as Mr. Hume's, he showed no farther hesitation in speaking.

"Yes, sir," he answered; "he said that Nature teaches us that there is no
God, because there is no need of any. He said that we cannot prove that
God created the universe, but that matter has existed from eternity
uncreated, and that all the changes in nature go on by certain laws of
development, and that a certain Mr. Darwin had written a book and proved
this."

The reader will notice that in the report of Mr. Hume's language the
scholar went somewhat farther than his master had done. Mr. Wilton was
well acquainted with the present shape of scientific infidelity, and saw
that Ansel's statements were somewhat exaggerated, but he understood in a
moment the drift of Ansel's thoughts, though he could not tell as yet how
deep and fixed an impression had been made upon his mind. But he did not
care to probe Ansel's conscience just then and there, in order to learn
the exact state of the case.

"If I understand you, then," he said, "you would like a course of lessons
in the teachings of Nature?"

"Of course, I did not suppose that you would allow us to have a course of
lessons in the works of Nature instead of the Bible."

"But if I were willing to give you a course of lessons showing the
footprints of the Creator, so to speak, in the physical world, how would
it please you?"

"I should like it very much."

"How would such a plan please the other members of the class?"

The idea was entirely new; no one of them had ever dreamed of studying in
a Bible class anything except the Bible; but young people are not averse
to novelties, and they readily gave their assent. Yet I should do the
class injustice by leaving the impression that they were influenced simply
by the love of something new. They were of just that age when one hardly
knows whether to call them lads or young men; they had been well
instructed, and were just beginning to think independently. They were
rapidly becoming conscious of their own mental power, and were eager to
try their strength upon every line of thought. Their own weakness they had
hardly begun to learn. Perhaps they were all the more ready to undertake
such a course of study because they knew nothing of the difficulties
attending it.

The tinkling of the superintendent's bell warned them to close their
conversation.

"We have not time to-day," said Mr. Wilton, "to fix on the particular line
of study which we shall follow. Of course we cannot examine all the works
of Nature, and study every science, and trace the footprints of the
Creator in every place where he has walked; we must fix on some small part
of the works of God, and direct our attention closely to that. We shall
find this course more profitable than roaming carelessly over a much
larger space. Our next lesson will have to be a general one--a kind of
preface to what shall come after. In the mean while, you can be collecting
your thoughts upon the subject, and calling to mind anything that you have
read bearing upon the handiwork of God manifest in Nature."

The school closed, and as the scholars pass out let me introduce to you
the members of the pastor's class. This class was small for several
reasons. The church to which Mr. Wilton preached was not the popular
church. The fashionable people and all who loved popularity and drifted
with the tide went to another church. Careless, thoughtless young people
naturally went with the crowd, and of those who attended his church some
did not care to join his class. He was too much in earnest to please them.
He made religion a reality, and his instruction compelled them to think,
and of course those who did not like to think were not well pleased with
him. But there were a few of the young men who were greatly interested in
his instructions. They were earnest readers of instructive books; they
liked conversation which called out thought; they were most of all
pleased with questions and themes which gave them new ideas. Indeed, in
the community, there were two classes of persons who held Mr. Wilton in
the highest esteem and regard: one of these was composed of men and women
of earnest, intelligent piety, experienced Christians; the other, of those
who were not Christians, but who respected sincerity and disinterested
godliness, and liked sermons filled with meat and marrow.

Thus, at the present time, we find his class composed of but three young
men. With Ansel you are already acquainted. The second is Peter Thornton,
the son of a master-carpenter. He was frank, outspoken, quick in the
acquisition of almost every kind of knowledge, but very little given to
silent reflection. He listened to his pastor's instruction as he would go
to a well-filled library, to draw out its stores of information. Morals
and moralizing he did not like. He was not pious, and gave no indication
of serious impressions. The third was Samuel Ledyard, the son of a poor
widow. By painful industry and economy his pious mother was giving him the
best advantages for education which the village afforded, praying the
Lord to give him a part in the blessed work of preaching the gospel and
winning sinners to Christ and salvation. When but twelve years of age he
gave himself to Christ, and had been trying faithfully to follow his Lord.
The long winter evenings were spent in reading books of history and
science--books fitted to furnish and strengthen his mind--and long ere the
light dimmed the morning star he was poring over his Bible, alternately
reading the word and praying that his mind might be opened to understand
the truth in its beauty and greatness, and that the truth might be wrought
in him by vital experiences.

With such habits it was no wonder that he grew in grace--it was no wonder
that he grew in all manly qualities. He was silent, meditative, and
retiring, as gentle in his ways as a quiet girl, yet all who knew him
recognized in him a singular weight and worth of character. Those to whom
the Lord revealed his secrets began to say that Samuel was appointed of
God to preach the gospel, and his mother felt the assurance growing strong
in her heart that her prayer was granted, and that the Lord was preparing
her only son and only child for a place in the gospel ministry. If only
she might train up a son to such a work, and when she should go to her
rest leave in her place a man working for Christ in his harvest-field,
gathering sheaves unto everlasting life, she felt that her cup would be
full. She was ready to say with Simeon: "Now lettest thou thy servant
depart in peace, for mine eyes have seen thy salvation." How unlike she
was to those mothers who lay all hindrances in the way of their sons
entering the work of the Christian ministry, willing that they should do
anything but this! and how different from those who declare that their
daughters shall never wed ministers of the gospel, teaching them to
despise the service of a pastor's wife! How often God gives over such sons
and daughters--children consecrated from their birth to worldliness--to be
entangled and lost in worldly snares! As such mothers sow, thus also do
they reap.

These were the three lads, just growing into young manhood, at this time
under the instruction of Mr. Wilton. He was not ashamed of his class,
though it was small. As he saw them expanding in thought and taking shape
under his hand, he felt that in them he was perpetuating his influence in
coming generations. He believed that in one or more of them he should
preach the gospel after his body was sleeping in the earth awaiting the
resurrection.

I trust the kind reader will be interested in following the course of
study through which their pastor shall lead them.



CHAPTER II.

NEW THOUGHTS FOR THE SCHOLARS.


The little class which has been introduced to the reader came together the
next Lord's Day interested and expectant, yet not knowing what to expect.
They had chosen a course of study, yet they could not tell what that
course was to be. They had tried to think of something definite about it,
but could fix their minds upon nothing. In fact, the whole subject was
new, and they could not decide where or how to take hold of it. They came
together, therefore, with no more knowledge of the subject than when they
separated.

Mr. Wilton himself came before his class in a state of doubt. He had given
the subject many hours of thought, and had carried it to his closet and
besought the guidance of the Holy Spirit, for he believed the divine
Spirit to be the best guide in understanding the works as well as the
word of God. He felt that his prayer had been heard and answered. He was
prepared, therefore, to speak with the force of clear understanding and
positive convictions. But the precise line of study he had left to be
determined by circumstances, perhaps by the previous studies of his class
in their academic course. This was to be decided by further consultation.

"Since no lesson was assigned upon which you could prepare yourselves,"
Mr. Wilton said, after the opening exercises of the school were finished,
"I shall spend the half hour to-day in a kind of conversational lecture.
You may call this the preface or introduction to the lessons which will
follow. I shall try to make plain some general principles which we must
keep in mind, whatever department of God's works we shall attempt to
examine. I wish you to feel entirely free to interrupt me at any time, and
ask any question or present any objection which may strike your minds. We
must, if possible, have no prowling bands of enemies in the rear. I wish
to make everything as plain as the case will admit.

"One thing let me remind you of in the beginning: I shall not try to prove
to you that there is a God. I shall not try to prove that the world had a
creator. There are some things which men do not believe merely on account
of good evidence, nor disbelieve for want of proof. Men believe in their
own existence, but not from a course of argument. Most men believe in the
real existence of the outward world--the earth, the hills, the rivers, the
trees, everything which we see and hear and feel--but not on account of
proof. Here and there a strange man is found who professes to disbelieve
the real existence of all material things, but he disbelieves not for want
of proof. Men believe that their sight and hearing and touch do not
deceive them, but their confidence in them is not the result of a course
of reasoning. To believe in our own existence, and in the existence of the
world outside of us, and in the truthfulness of our senses, is natural; to
disbelieve these things is unnatural: it shows a state of disordered
mental action. When such disbelief is not practically corrected by a man's
understanding he is counted insane, and is treated accordingly.

"Belief in the existence of God is also a natural belief. A denial of
God's existence shows, not disordered mental action, but a disordered
moral and spiritual state. It shows the absence of that spiritual faculty
by which we receive spiritual impressions, and are brought into contact
with the spiritual world, and hold intercourse with God and Christ and the
Holy Spirit. Men must be convinced of the existence of God through their
conscience, their moral and spiritual nature. Do not misunderstand me. I
do not say that good evidence cannot be brought to prove to one's reason
the existence of God, but God has not left his existence to be _proved_:
he has _revealed_ himself to men's consciences and to their faith; and
those in whom conscience and faith are well developed, sound, and right do
not need an elaborate argument to prove the divine existence. I shall
simply try to show that the works of creation exhibit the wisdom and
goodness of God. If any man, looking at such indications of wisdom and
kindness, can believe that it all comes by chance or is the work of some
evil agency, and that no Being of boundless intelligence, wisdom, power,
and goodness has anything to do with the making and governing the world,
he certainly shows great prejudice: he does not want to recognize God's
existence. He must be one of those spoken of by the Psalmist who say, 'no
God.'

"During my recent visit to Greenville I visited a mill, the largest of its
kind in the country. In one room was a machine, something like a huge
straw-cutter, working with great power. In another room was a large steam
boiler hung upon a shaft and made slowly to revolve while filled with
steam. In a third room were large oval tanks, or cisterns, which might be
filled with water. Across each tank was a heavy shaft carrying a drum set
with steel blades, and as the drum revolved these blades passed other
blades in the bottom of the tank, cutting whatever came between like
scissors. In a fourth room were certain long and complicated machines.
Each machine was composed mostly of rollers. There were large rollers and
small rollers, solid rollers of enormous weight, and hollow rollers to be
heated by steam within. Over and around a portion of these rollers passed
a broad wirecloth belt. Over others passed a like belt of felted cloth.
With these machines before you, could you tell me whether the inventor
were a wise and skillful machinist?"

"How could we tell," asked Peter, "without knowing what kind of work the
machine was designed to do?"

"You could not tell," answered Mr. Wilton; "you would need to know both
what the machine was designed to do and all the processes by which the
work was to be carried on. This brings out the first point which I wish
you to fix in mind. It is this: To judge of the wisdom of any contrivance,
we must understand the purpose, or object, which the inventor had in view;
we must understand the work to be accomplished, and also the difficulties
to be overcome. An ordinary locomotive steam-engine is admirably fitted to
run on iron rails, but he would be a foolish man who should purchase such
an engine to draw a train of loaded wagons over a common road of earth. On
such a road it could not even move itself. It is good for that for which
it was made, and for nothing else. How would you apply this principle to
the subject we are now considering? You may answer, Samuel."

"I think you mean," said Samuel, "that, in order to judge of the wisdom
and goodness of God in creating and governing this world, we must know
the object he had in view in making such a world."

"That is my meaning, and I am glad that you understand me so perfectly. If
this world were created with no other object than to be the grazing-field
for herds of cattle, which see no difference between the beauty of the
violet and the dull shapelessness of the cold earth upon which it grows,
and never lift their eyes above the horizon, then all the beauty of earth
and sky would be useless; there would be no wisdom or goodness in the
creation of this beauty. There would be no wisdom or goodness in laying up
in store beds of coal, buried deep beneath the surface of the earth, if
God designed the world to be inhabited only by savages too rude and
ignorant ever to mine it, and turn it to some practical use.

"But let me give you another illustration, which can better be applied to
the condition of things in this world. Just in the outskirts of one of our
inland cities I once saw a large and elegant building, whether a private
dwelling or a public institution I could not at first tell. It stood high
and airy, commanding the most pleasing prospect that all the region
presented. We will follow a visitor as he goes to examine that noble
establishment.

"As he comes nearer, he sees that the edifice is simple and classic in its
style and chaste in its architectural adornment. It is a pleasure for the
eye to rest upon its graceful symmetry. But in place of the light and
graceful fence which he expects to find enclosing its grounds, he sees a
stockade strong and high. The janitor turns the heavy key, the rusty bolt
flies back, and the visitor enters the enclosure. Within the stockade he
finds a portion of the ground laid out with taste and cultivated with
choice and beautiful flowers; another part is devoted to the culture of
garden vegetables. He finds workshops also for the manufacture of pails
and tubs, brooms and mattresses. The visitor is ushered into the mansion
itself. He finds everything more than comfortable; the rooms are heated
from furnaces below; every part is perfectly ventilated; the windows
command a view of the country around which must please the most cultivated
eye; a school-room is provided with all needed apparatus for the most
thorough instruction. 'Surely,' says the visitor, 'the founder of this
institution must have been both wise and good. He must have loved the
young in order to study and supply all their needs so completely.' But
some things strike the visitor painfully. The windows are grated with
iron, and some of the rooms are almost like prison cells. 'Can it be
possible,' he thinks within himself, 'that the young need to be confined
by a stockade in so pleasant a place and shut in by grates of iron for the
enjoyment of such advantages?' The master as he teaches his pupils seems
as kind and gentle as a mother, yet there is a firmness and authority in
his tones and a rigidity in his training, as if his government were kept
braced against a mutinous spirit. The means of punishment also are
provided, and, when occasion requires, stern chastisement is employed. All
this seems to the visitor like an enigma. The institution appears to him
like a bundle of contradictions. A father could not have provided a
pleasanter home or larger advantages for his children, but fathers do not
commonly surround their homes with stockades, and cover their windows with
bars of iron, and train their obedient children with a hand of such firm,
unyielding force. 'Pray, sir,' he says to the master, 'what is this
strange contradictory institution?' 'It is the State Reform School,' the
master answers. 'And who are these lads and young men for whom all this
work and wisdom is expended?' 'They are those who have taken the first
steps in crime, but have not as yet become hardened and fixed in
wickedness, and are sent here with the hope of overcoming their vicious
propensities and training them to virtue and an honorable manhood.'

"Everything is now made plain. The need of the stockade, and the grated
windows, and the rigid government, as well as of the pure air, the
garniture of beauty, and the kind loving care, is manifest. It is a place
unsuited to a family of obedient children, and equally unsuitable as a
place of confinement for confirmed criminals, shut up, not for reform, but
for punishment. It is wisely adapted to the work designed to be
accomplished, and to no other.

"In like manner, if we would judge of the wisdom and goodness of God in
the creation and government of this world, we must understand the use for
which the world was designed. Is this plain to you, Ansel, and does it
seem reasonable?"

"Yes, sir; I think I understand it, and I can see no objection to the
principle. I think even Mr. Hume could find no fault with that. But how
shall we know the object for which God made and governs the world?"

"That is the next point to be considered. Perhaps you will tell us what
seems to you to be that object? Young people sometimes have thoughts and
opinions upon the greatest questions."

"I have never formed an opinion of my own," Ansel replied, "but I have
always heard it said that God designed to show how perfect and good and
beautiful a world he could make. But many things in the world seem to me
neither perfect, nor good, nor beautiful."

"Why, Ansel!" exclaimed Samuel; "the Bible says that 'God saw everything
that he had made, and behold it was very good.'"

"And, Mr. Wilton," asked Peter, "does not the Bible say that 'God created
all things for his own glory'?"

"Before answering any of these questions, let me ask Samuel a question.
What do you understand to be the meaning of the words you quoted from the
last verse of the first chapter of Genesis?--'God saw everything that he
had made, and behold it was very good.'"

"I suppose it means," answered Samuel, "that God made everything just as
good and beautiful as it can be, so that any change must be a change for
the worse. The lecturer last winter said that if men could entirely
destroy any one of the most troublesome species of insects, their
destruction would be a great loss to the world, and that if a single atom
of matter belonging to the earth were annihilated, it might throw the
solar system out of balance, so that it would finally be destroyed."

"I remember," said Mr. Wilton, "that some lecturer last winter made
statements of that kind, and I have heard other people declare that the
least possible change in the world would be injurious, if not destructive,
to the interests of man, and that the most troublesome beasts and insects
and the most loathsome reptiles are necessary to human happiness. Does
that seem to you to be true, Samuel?"

"I have always tried to believe it, because I thought I ought to believe
it. It has seemed to me to be dishonoring God to believe that he did not
make the best possible world."

"You are right in trying to believe what seems to be right and true, even
though difficulties do lie in the way. Difficulties do not by any means
show that an opinion is false. We must certainly believe that God made
this world perfect for the object which he had in view in making it. But
not a few skeptics deny the existence of a good, wise, righteous Creator
and Governor, because they have a wrong idea of the end for which the
world was created, and, consequently, a wrong idea of that in which its
perfection must consist. Let me ask you a few questions which will lead
your minds in the right direction. Do not men produce by cultivation
better fruits and vegetables than Nature ever grows when left to herself?"

"Yes, sir," said Ansel; "the peach and apple and potato have been brought
up to their present state of excellence by great care and exertion.
Originally, they were almost worthless."

"And not only that," said Mr. Wilton, "but when once that careful culture
is relaxed they begin to return to their former badness. Again, do we not
improve upon Nature by drainage and improve upon the climate by
irrigation?--in fact, do not men by drainage and irrigation and all
manner of culture greatly improve the natural climate of a country?"

"I think that is true," said Ansel.

"I never thought of that before," said Peter.

"Moreover, do you not suppose that heaven will be more beautiful than the
earth, and that a thousand troublesome things besides sin--loathsome
sights, discordant and jarring noises, disgusting and nauseous odors--will
be absent from that 'better land'?"

"And _I_ never thought of that before," said Samuel. "I am sure that many
unpleasant things besides those which sin has brought into the world will
not be found in heaven. I see that this world might be changed and not be
made worse for holy beings to live in."

"The world is very good," said Mr. Wilton, "for the purpose for which it
was created, but we need not look upon it as designed for a specimen of
the most beautiful, pleasant, and desirable world which the Creator could
produce."

"But you have not told us," said Peter, "what the Bible means when it says
that God created all things for his own glory. Does it not mean that he
made the world so good and perfect that all creatures ought to praise him
on account of it?"

"We ought," said Mr. Wilton, "to praise God for the wisdom and goodness
displayed in the works of creation. That is the teaching of the Bible in
many places; it is also the sentiment of the Bible that God created the
world and carries on all things for his own glory, but it nowhere uses the
exact language which you have employed. In Isa. xliii. 7, speaking of
'every one that is called by my name,' the Lord says, 'I have created him
for my glory.' In Prov. xvi. 4 it is written, 'The Lord hath made all
things for himself; yea, even the wicked for the day of evil;' and the
four and twenty elders fell before the throne of God saying: 'Thou art
worthy, O Lord, to receive glory and honor and power; for thou hast
created all things, and for thy pleasure they are'--that is, exist--'and
were created.' I might quote other texts of similar meaning. We are taught
also that our first and supreme aim in all our conduct should be the glory
of God. 'Whatever ye do, do it all to the glory of God.' But here two
questions arise: What is the glory of God? and, What is it for God to
glorify himself by his works of creation and government? Who will tell
us?"

All were silent, and Mr. Wilton went on speaking: "The word glory means,
first and literally, a halo of light. The glory of God is the radiance, or
halo, so to speak, of his infinite attributes and holy character. God
glorifies himself when he reveals himself, and makes known his character,
and causes the uncreated splendor of his attributes to break forth, so
that his creatures recognize them and adore him. This, you see, is very
different from the idea of glory among ambitious men. God glorified
himself in the creation of the physical world, because from that creation
his wisdom, power, and goodness are manifest. He glorified himself in the
creation of angels and men, because they were created in the image of God
and are finite pictures, so to speak, of the infinite Creator--a
revelation of his spiritual being and personality. He glorifies himself in
his government of the world, because his administration of affairs
exhibits his justice, mercy, and holiness. This is what we mean by the
glory of God and his working all things for his own glory. This is
somewhat difficult for persons of your age, so we will leave it and
return to the exact subject of discussion. Admitting that God created the
world and governs it for his own glory--that is, to reveal himself--for
what specific purpose did he design this earth?"

"I don't know," said Peter, "that we understand what you mean by 'specific
purpose.'"

"Very well, then," said Mr. Wilton; "I will suggest the answer. Does the
world seem as if fitted up to be the dwelling-place of holy beings?"

"I have never thought of the question before," said Ansel; "but it seems
to me that many things in this world would give pain even to angels if
they lived here with bodies like ours."

"I agree with you, Ansel. If men were sinless and holy as the angels of
heaven, many things in this world would bring them distress. But does it
seem reasonable that the world was designed merely as a place of
punishment for men by reason of their wickedness?"

"Some men are not wicked," replied Samuel. "There have always been men
willing to die rather than disobey God. Surely, God does not punish such
men. And many beautiful and pleasant things are found in the
world--arrangements plainly designed for the welfare and happiness of
men."

"I think you are right, Samuel. But, without asking further questions, I
will give you the conclusions to which my study upon this subject has
brought me, and some of the reasons for those conclusions.

"This world was made chiefly as the dwelling-place of man. The world was
not planned merely as the abode of brute animals. Men are nobler than the
brutes. Men have permanent interests and advantages. Aside from the glory
of God, men are an end unto themselves. To become and be _men_ is the
noblest object of human life, but the animal tribes exist for the use and
benefit of others. To be an end to itself, a creature must be immortal;
but the brutes exist for the use and advantage of man, live out their
transient life, and exist no more. This is the view presented in the
sacred Scriptures. God gave to man lordship over the earth--not only over
the soil to subdue it, and over the great forces of Nature to bring them
into subjection for human advantage, but also over the brute creation,
'over the fish of the sea, the fowls of the air, and every living thing
that moveth upon the earth.' I conclude also that God did not prepare this
world as a prison-house and place of punishment for rebels against his
government. Too many pleasant things abound for me to believe that. The
pleasant breezy air, the glorious sunlight, the refreshing showers, the
treasures of mineral wealth stored up in the earth, the fertile land and
golden wheat, the beauty spread over all nature, the sweet consciousness
of existence, so that just to live and act is joy, and the comfort and
hope of immortal pleasure enjoyed by truly Christian men,--all these
things, and many more, assure me that not the subtle shrewdness of a
tormentor nor the unmingled justice of an inexorable judge, but the heart
of a kind and loving Father, planned our earthly dwelling-place. You said,
Samuel, with truth, that there are many pious men in the world who are
dear to God, and Paul says, 'We know that all things work together for
good to them that love God.' For those dear ones Christ has such love that
he counts everything--whether good or bad--that is done to them as if done
to himself. 'Inasmuch,' he says, 'as ye have done it unto one of the least
of these my brethren, ye have done it unto me.' Moreover, Jesus said:
'For God so loved the world, that he sent his only begotten Son, that
whosoever believeth in him should not perish, but have everlasting life.'
From these words of Jesus we see that there is love manifested in the
dealings of God with the inhabitants of our world. Were it not so, there
would nothing remain but a 'fearful looking-for of judgment and fiery
indignation, which shall devour the adversaries.'

"On the other hand, I conclude that God made the world as the
dwelling-place, not of obedient, holy children, but of those who are
disobedient, fallen, and alienated. These disobedient and alienated ones
he holds under discipline and chastisement, in order to keep their
wickedness in check, to recover them from their sins, and train them up in
virtue and holiness, or to remove from the obstinate and incorrigible all
excuse for their sins and all plea against their final condemnation. In
doing this he glorifies himself by manifesting his wisdom, goodness,
mercy, and holiness.

"This opinion seems probable from the fact that this is the purpose for
which God has actually used and is now using the world. Here he keeps and
governs the human race. This race is made up neither of holy beings nor of
hopeless reprobates. They are the creatures of God; fallen indeed, yet
loved; sinful, but objects of divine compassion; deserving of righteous
wrath, but the recipients of the offers of salvation through Christ. Even
penitent believers in Christ and devoted servants of God are not free from
evil propensities, but need to be kept under constant training and
discipline. This is the use to which the Creator has actually put the
world. Is it not reasonable to believe that he designed it for their use?
Ought we to believe that God planned the world for an object for which it
never has been and never will be employed?

"If sin were removed from the world, the chief part of human suffering
would be removed. This no man can deny. Wars would cease; the want,
disease, and woe resulting from selfishness, idleness, and vice would
disappear, and nothing would stand between man and his Maker. What new
life and joy would fill the world if free communication were restored
between man and God, and the divine smile were again to enlighten the
world! It would seem that heaven had enlarged her borders to embrace this
earthly ball. But the fact would still remain that this physical world is
unfitted to be the dwelling-place of sinless beings. The constitution of
the world would bring upon them pains and evils which would seem a most
unworthy heritage for loving and obedient children of our heavenly Father.
Let sin be taken away, and wearisome toil in subduing the earth would
remain. The soil of the earth is hard and clogged with stones, and clammy
with stagnant waters, and sown well with the seeds of noxious weeds, and
overgrown with thorns and thistles. Endless watchfulness and toil is the
price of a livelihood. With the sweat of his face man must eat his bread.
An army of enemies have pre-empted the soil which man must till. This
state of things the word of God refers to sin: 'Cursed is the ground for
thy sake; in sorrow shalt thou eat of it all the days of thy life. Thorns
also and thistles shall it bring forth to thee.' The necessity of toiling
as we do now for our daily bread, God denounced upon man as a curse on
account of sin. We cannot, therefore, regard this as a suitable condition
for sinless beings.

"This burden of toil is lightened by the progress of modern sciences and
inventions much less than some men think. Every step of progress has been
made by the sacrifice of hecatombs of human lives. From our laboratories
and workshops products of human skill, rich and rare, are sent forth; but
what are they but smelted and hammered and graven and woven human bones
and sinews, the health and life of men? No means have been discovered by
which the most necessary processes of the arts can be made otherwise than
dangerous to health. Only when thousands of miserable workmen had perished
was Sir Humphrey Davy's safety-lamp invented; and now the danger, to say
nothing of the hard toil, of the collier's life is only lessened, but not
removed. Still, our furnaces roar and the whole tide of civilization goes
on by the health-destroying servitude of men, buried alive as it were in
the dark bosom of the earth. Would that seem to be a fitting employment
for the sinless children of the all-loving Father? Employés in many kinds
of manufacture slowly sink under the accumulated evils of daily toil, and
no means of making their employments healthful have been discovered. The
friction-match, which has become so nearly a necessity, is made by a
process so destructive to health that only a certain class of laborers can
be prevailed upon to do the work. I might go on to speak of other painful
circumstances in which men find themselves by the almost antagonistic
attitude of Nature. But if we reject these dangerous processes of
manufacture and art, we go back at once to the wooden plough, the distaff
and tinder-box of primitive times, and also to primitive poverty and
primitive toil, and, I may also add, to primitive exposure to the hostile
and pitiless forces and inclemencies of Nature. Purge the earth of sin,
and wearisome toil would still remain. Nature must be nursed and
cultivated or she yields no bread. Her hostile attitude must be overcome;
the thorns and thistles must be rooted out; and every step of progress,
won by suffering, must be held by painful work and watchfulness; otherwise
Nature returns to the wild and savage state. Relax the culture of the
choicest fruit, and it begins to deteriorate; leave the best-blooded breed
of cattle to itself, and it returns again to the level of native,
uncultured stock.

"The inhabitants of this world are also liable at all times to diseases
and destructive accidents. This condition of things could not be changed
without changing the entire structure and plan of the world. Is that a fit
dwelling-place for a sinless being where chilling winds one day shrivel
his skin and fill his bones with rheumatic pains, and the next, sweltering
heats pervade all his system with languid lassitude--where miasma lies in
wait unseen to poison his blood, kindle the malignant fever, and bring him
to the shades of death, and every form of accident crouches in ambush,
ready to spring upon his victim unawares and tear him limb from limb? We
cannot see that the absence of sin would dissipate this liability to
disease and the danger of accidents. Nay, this liability and danger are
written upon the very constitution of the human body. The finger of God
has engraved it upon every muscle and bone and life-cell. The Creator gave
the body that wonderful power called the _vis medicatrix_--the power of
recovering from injuries and repairing damage done to itself. Pull a leg
from a grasshopper and another grows in its place. By this we know that
the Creator understood the liability of this little insect to lose a limb,
and prepared him for it. In like manner the power in man's body to heal a
wound or join a broken bone gives us to understand that the Creator
expected man to live in the midst of danger. The precaution proves the
risk.

"These accidents are such as no possible carefulness could guard against.
To say nothing of the fact that all our knowledge of these perils comes
from a painful experience of danger and death, what care, even after ages
of sad experience, could ward off the thunderbolt? What carefulness could
guard against the tornado on the land, or the hurricane and the cyclone
upon the sea? Who should stand sentinel against the unseen poison borne
upon the wings of the wind? What power should save him from the bursting
of the volcano and the jaws of the earthquake? What care could give him
knowledge of the qualities of all natural substances, that he might avoid
their dangerous properties? We can suppose a divine care over man that
should do all this and save men from harm, but it would be a providence
superseding all human knowledge and exertion--it must be a providence to
which the human race is now a stranger; miracles would then be the rule,
and the undisturbed course of Nature the exception.

"If, however, we suppose that God designed the world as a training-school,
so to speak, of fallen beings, such as the word of God declares the human
race to be, all is plain, everything is suitable and harmonious. We can
see the fitness of at least the chief outlines of man's earthly condition,
and can perceive God's wisdom and goodness in the constitution of the
world.

"The pain and woe-producing agencies of Nature are seen to be not at all
contradictory to goodness, but on the other hand eminently wise and
righteous. The whole sum of human misery expresses God's displeasure at
sin. By their sufferings men learn how abhorrent is sin in God's sight. By
the consequences of evil-doing they learn not to transgress. As none are
free from the taint of depravity, none are free from pains. The necessity
of labor--one of the elements of the primal curse--is a check to sin on
the part of the vicious, and a discipline and trial to virtue on the part
of the penitent. The multiform trials of life--which can indeed be borne
well only by the grace of God--while they teach the evil of sin and keep
the heart chastened and subdued, nourish heroic and dauntless virtue in
the faithful. 'Daily cares' become 'a heavenly discipline.' Dangers and
calamities startle the stupid conscience, and keep alive the sense of
responsibility to God on the part of the wicked; they quicken the sense of
weakness and dependence in the believing and educate their faith in God.
The more sudden and overwhelming these evils, and the more these dangers
are placed beyond the possibility of being warded off by human care, the
more do they awaken in men a sense of the divine presence and of
responsibility to God.

"But would not all these natural agencies subserve essentially the same
ends in the discipline of unfallen and sinless beings? By no means. If
sufferings came upon a sinless being, he could not feel that they came as
chastisements; he could not feel them to be deserved. They would be to him
a 'curse causeless,' and hence would bring no advantage. He could only cry
out in astonishment, 'Father, why am I, thine obedient son, thus smitten?'
Calamity falling upon the innocent would be an anomaly in the universe.
But now the sufferer, pierced through and through with a sense of ill
desert, meekly bows his head, murmuring, 'Father, all thy judgments are
just and right.'

"One very important feature of the world we live in is its moral
symbolism. The world is full of most suggestive symbols and emblems of
moral good and evil. There are all beautiful and glorious things, to stand
as types of goodness, truth, and righteousness; there are all loathsome,
malignant, and hideous things, to serve as the types of folly and
wickedness. Was it merely an accident that the dove was fitted to become
the emblem of purity and of the Holy Spirit? the lamb, to be the emblem of
gentleness, of Christ the gentle Sufferer, and of his suffering people?
the ant, to be the type of prudent industry? the horse, of spirit and
daring? and the lion, of strength and regal state? Was it only an accident
that prepared cruel beasts and disgusting, poisonous reptiles as the types
of evil passions and sins--that made the venom of the viper, the cunning
of the fox, the blood-thirstiness of the wolf, the folly of the ape, and
the filth of the swine, symbols of foul, subtle, malignant sin and folly?
Nature is full of these emblems. The palm tree with its crown of glory,
the cedar of Lebanon, the fading flower and withering grass, the early dew
and the morning mist, the thorn hidden among the leaves of the fragrant
rose, poisons sweet to the taste, and medicines bitter as gall,--how all
these natural things preach to men sermons concerning spiritual verities!
There is no virtue or grace which is not commended to man by its image of
beauty in the animal tribes; there is no vice against which men are not
warned by its loathsome, disgusting form shadowed out in the instinctive
baseness of irresponsible brutes.

"Thus we find earth, air, and sky to be full of silent voices proclaiming
in the ears of man that which he most of all needs to remember. These
types and symbols of virtue and vice are specially needed by fallen
beings. They seem fitted for beings whose spiritual eyes are blinded and
all their spiritual senses blunted--beings with whom there is no longer
'open vision' of spiritual realities. These pictures of evil are most
impressive to men who see in them the reflection of their own base
passions. How the fetid goat and the swine wallowing in the mire speak to
the lecherous man and the drunkard! In a world of sinless beings these
mimic vices would seem rather to mar God's handiwork.

"Set the human race, fallen as it is, in a world where the patience of
daily industrious toil would not be needed, and the race would rot with
putrid, festering vice. Remove all danger, and men would forget and deny
that the Creator holds them responsible. Let no evil consequences follow
evil-doing, and men would cease to make a distinction between right and
wrong. Take away death, and they would deny the existence of a spiritual
world. But in this world God has hedged men around with checks and
penalties and painful discipline, such as are of use only in dealing with
sinners.

"I conclude, therefore, that God prepared this world as it now is as a
place of discipline for a fallen race. This is the use to which he has
devoted it in the past; and when there is no longer need of such a world
for the discipline of men, we learn from the word of God that a 'new
heaven and a new earth' shall be provided. This world is thus declared to
be an unfit abode for the glorified saints. To judge, then, of the wisdom
and goodness of God in the works of nature, we must keep in mind the
object for which the Creator prepared the world. Ansel, tell us how this
strikes you."

"I never thought of it in this way before," he answered; "indeed I have
thought very little of this subject, but--" Tinkle, tinkle went the bell
upon the superintendent's desk. This was the second time the
superintendent had struck his bell, but Mr. Wilton had been so intent upon
his subject that he did not hear the first ringing.

The school was dismissed, but Mr. Wilton remained with his class to fix
upon the particular department of nature which they would study. He found
that all were studying natural philosophy, and had recently gone over the
subject of heat. At his recommendation, therefore, they agreed to examine,
as a specimen of God's works, his management of heat in the world. Mr.
Wilton requested them to review the subject during the week, and be
prepared to state and apply the general principles touching the nature,
phenomena, and laws of heat which they had already learned. This work they
will enter upon next Lord's Day.



CHAPTER III.

A DIFFICULT QUESTION.


During the week, Ansel, Peter, and Samuel were busy reviewing and fixing
in memory what they had already learned of the nature and laws of heat.
They were not only interested in the new line of study, and desirous of
pleasing Mr. Wilton, but they also felt that their scholarship was to be
tested, and each one was ambitious of standing equal to the best.

Ansel, of course, was busy and ambitious. The lesson was coming somewhat
upon his own ground, and he felt in no wise unwilling to show how well he
had mastered the subject. He entered upon it with feelings a little
different, however, from his anticipations. The explanation which Mr.
Wilton had given of the purpose of the Creator in making such a world
seemed to him very reasonable. He could make no objection to it. But that
explanation had taken away at one sweep a whole store of objections to
God's goodness which he was waiting to bring out as soon as a good
opportunity was presented. A world designed for the dwelling-place of
sinners--sinners not already given over and doomed to final wrath, but to
be recovered from sin and trained in virtue and holiness, or, if
incorrigible, to be held in check and used as helps in the discipline of
the righteous--he plainly saw must be as unlike a world fitted up for holy
beings as a reform school is different from a home for kind and obedient
children. Those arrangements which he had thought the most painful and
objectionable might, after all, be the wisest and best. He did not see
where to put in a reasonable objection to Mr. Wilton's unexpected
argument, yet he did not feel quite satisfied to confess to himself that
he was so soon and so easily defeated.

In this state of mind, on Saturday morning he met Mr. Hume upon the
street.

"Good-morning, Ansel," said Mr. Hume.

"Good-morning," returned Ansel.

"I hear," said Mr. Hume, "that you have given up studying the Bible in
your Bible class, and have begun the study of natural philosophy. Is that
so?"

"Not quite true, Mr. Hume. We are to examine some department of the works
of Nature, and see what indications appear of the Creator's wisdom and
goodness."

"That is a little different from the report which came to me. But what did
you learn last Sunday?"

"Mr. Wilton told us that in order to judge of the wisdom and goodness of
God in any of the affairs of this world we must consider the object for
which that arrangement was designed. He said that if a man examine a
cotton-gin, supposing it to be a threshing-machine, he would be likely to
pronounce it a foolish and worthless contrivance; and that the fine edge
of a razor would be worse than useless upon the cutter of a breaking-up
plough. He told us that the earth was not prepared as the dwelling-place
of sinless beings, but as a place of discipline for the fallen human race,
and that we ought not to look upon it as the choicest specimen of
workmanship which the Creator could construct."

"I have heard that Mr. Wilton believes something of that kind. Ansel,
have you studied geology?"

"I have read a little upon that subject and have heard some lectures."

"Can you tell me, then, whether or not the natural laws which prevailed on
the earth ages and ages ago, before the earth was fit for men to live upon
it, are the same as those which have been in operation in these later
ages, since men have inhabited it?"

"I suppose that the same laws have prevailed from the beginning of the
geologic periods. I think that geology makes that very evident."

"If that were not so," said Mr. Hume, "the past history of the globe would
be a riddle to us; it would be confusion worse confounded. In regard to
those early ages we could not reason from cause to effect, for we should
know nothing of the forces and principles then in existence. In geologic
studies we judge the past from the present, and if that be not a
trustworthy method of reasoning, all the conclusions of geologists are as
worthless as dreams. Have you any reason to suppose, from what you have
read on this subject, that a curse changed the character of the earth as a
dwelling-place for man some six thousand years ago? Is it true, as Milton
says, that then

                                          'The sun
    Had _first_ his precept so to move, so shine,
    As might affect the earth with cold and heat
    Scarce tolerable, and from the north call
    Decrepit winter--from the south to bring
    Solstitial summer's heat'?

Did the Creator then

                      'Bid his angels turn askance
    The poles of earth twice ten degrees and more
    From the sun's axle'?

Or was death then first introduced among the brute creation, as Milton
fancies?--

                      'But Discord first,
    Daughter of sin, among the irrational
    Death introduced through fierce antipathy;
    Beast now with beast 'gan war, and fowl with fowl,
    And fish with fish; to graze the herb all leaving,
    Devoured each other.'"

"Animals must have died," said Ansel, "for their remains lie imbedded in
rock which certainly existed before man lived on the earth."

"I wish you would ask Mr. Wilton one question for me."

"I am willing to ask him any proper question, and I suppose you would not
wish me to ask any other."

"I certainly would not. Will you ask him how it was possible for man not
to sin and fall if God created the world for a sinful race myriads of ages
before man was brought into existence? It would seem that if man had
remained obedient he could not have lived pleasantly in a world prepared
for sinners, and at the same time, by man's obedience, all the Creator's
plans touching this world would have been dislocated and disappointed."

"I will ask him, sir," said Ansel, "at the first good opportunity."

This good opportunity occurred sooner than Ansel expected, for, before
entering upon the proposed lesson the next Lord's Day, Mr. Wilton said to
the class:

"I wish in these lessons to advance carefully and safely, and, as far as
possible, have everything well understood. For that reason I invite you to
speak freely of any difficulties or objections which may suggest
themselves to your own minds or which you may hear presented by others. At
the close of the last lesson the views which I had presented to you seemed
very reasonable, but it is possible that, as you have thought upon the
subject during the week, objections may have arisen in your minds. If so,
I should be glad to hear them now."

"There are many things," said Peter, "of which I cannot see the use, even
if we suppose that the earth was designed as the dwelling-place of
sinners."

"It would be very surprising indeed if you could unravel all the mysteries
of creation in a week's time. Wiser men than any of us have spent a
lifetime in searching out the meaning of God's works, and died still in
the dark upon many points. We need not expect to unravel and understand
all the deep, complex, and delicately-interwoven contrivances in a world
so vast and curious as this. The world is a great mystery--mysterious as a
whole, and mysterious in all its parts--upon any supposition. But the
explanation which I gave of its design furnishes a sufficient reason for
the great outline of creation. This gives a reason for the pains and
miseries which dog man at every step. This gives a reason for the earth's
being left rugged and sluggish, bringing forth thorns and thistles, and
requiring to be subdued by patient industry. It shows a ground for the
necessity of exhausting toil under a frowning sky and mid miasmatic
airs--for the liability to diseases and accidents, and the hard necessity
of death. These great elements of divine providence are not stripped of
their halo of mystery, but with this explanation they are seen to form a
harmonious whole for the accomplishment of a great and glorious purpose."

Mr. Wilton paused. Then Ansel said, "Mr. Hume wished me to ask you a
question."

"Very well, I should be glad to hear it. I hope, indeed, that he sends his
question from interest in the subject, and not with the design of
perplexing us. I wish also that he were here to ask the question and hear
the answer for himself. But what is the question?"

"He wished me to ask how it was possible for man not to sin and fall if
God placed him in a world prepared for a race of sinners and unfitted for
a sinless race. He said that in such a case, if man had remained obedient,
the plans of God would have been disarranged."

"What answer did you try to give him, Ansel?"

"I did not try to make any explanation. It seemed to me a very great
objection. I did not see how such a course was consistent with God's
righteousness."

"And you are not the first person who has objected to this as a great
inconsistency. I am afraid the discussion will take more time than we
ought to spare, but now that the question has been asked and the objection
presented, I must take time to answer it, even if it consume the whole
half hour.

"In considering this subject, as well as many others, we need to remember
that the existence of difficulties is no objection to a principle or a
fact. Difficulties wholly inexplicable by man attend facts and principles
which must be true. A fact may be incomprehensible, though undeniable. The
great Doctor Johnson said, 'There are insuperable objections against a
plenum, and insuperable objections against a vacuum, yet one of these must
be true.' What did he mean by that, Samuel?"

"He meant, I suppose, that we could not explain the possibility that any
space should be wholly empty of matter, and could no more explain the
possibility that any space should be filled with matter, but that all
space must be filled, or else there must be empty space. Whether we can
explain the possibility or not, one of them must be true."

"That is right. The same is true of many other facts besides a plenum and
a vacuum. We cannot conceive of infinite space; we cannot conceive that
space should not be infinite, but bounded. We cannot conceive of the
creation of the world from nothing, and no more can we conceive of its
eternal existence. The truth is that the mind of man cannot grasp such
subjects so as to reason upon them correctly. No sooner do we attempt to
reason about the infinite things of God than we run into absurdities and
reach the most contradictory conclusions. And in this respect it makes no
difference with what principle or proposition we start if it only contain
some infinite element. Let me give you a simple illustration from
geometry--an illustration which, very likely, is familiar to you: the
larger a circle, the less is the curvature of the line which bounds it;
that is, the more nearly does that line approach a straight line. An
infinite circle must be bounded by a straight line, because with any
degree of curvature the circle would be less than infinite. But a
straight line cannot bound a circle. The attempt to reason about an
infinite circle brings us at once to the most palpable absurdities and
contradictions. Or take this illustration: the whole of a thing is greater
than any of its parts. But divide a line of infinite length in the middle,
and each part is infinite. We reach the conclusion either that the half is
equal to the whole or that other wholly incomprehensible proposition, that
one infinity is twice as great as another infinity. I have made these
statements to show you that the existence of difficulties does not
indicate, much less prove, that a fact is not real and true.

"Mr. Hume thinks the fact that the earth existed in its present condition
before men sinned an insuperable objection to the view that this world was
prepared as a place for the discipline of a fallen race. But let us look
at the other side, and see if equal objections do not exist. The Creator
foresaw the fall of man; is there no objection to the supposition that,
knowing that man would sin, God made no provision for it? On the one
supposition he foresees the evil and makes no provision; on the other, he
foresees it and provides for the catastrophe. The former supposition
certainly involves the greater difficulties.

"The objector may reply that the plan of God, by embracing the fall of man
and including it as one of its essential elements, made that fall
necessary. But why should not God embrace in his plan that great event,
the fall of man, which he foresaw in the future? Would it have been wiser
and better to leave out of account that most stupendous fact in the
history of the human race? This same objection, which Mr. Hume and many
others have brought forward, lies with equal force against the great
central fact of the gospel, the death of Christ. God's plan touching this
world included the incarnation and death of his Son. Jesus, the 'Lamb of
God,' is spoken of as 'slain from the foundation of the world.' Rev. xiii.
8. But the incarnation and death of Christ presuppose the apostasy of the
human race. Did this plan touching Christ make the apostasy of man a
necessity? If preparing a world--fallen, so to speak, beforehand--for a
race which God foresaw would fall, be inconsistent with his righteousness,
it must be equally inconsistent to prepare a Saviour beforehand for that
same race.

"Again, the divine plan touching the death of his Son included his
betrayal by Judas and his crucifixion by the Jews. If Judas had known that
God had poised the salvation of man upon the pivot of his treachery, he
would doubtless have argued as Mr. Hume and others are accustomed to do.
But did God's plan excuse his treason against his Lord? His own
conscience, piercing and rending his soul with remorse, drove him to
self-destruction, and Christ confirmed the sentence of his conscience and
called him the 'son of perdition.' The fact that God weaves the foreseen
crimes of men into his plans is no palliation of their guilt.

"Would it be wise and well to take no account of foreseen events? Jesus
has gone to prepare mansions for those who will, as he foresees, believe
in him: why not make provision for foreseen evils also? Our civil
government, knowing the liability to crime among men--a liability which
the experience of man has shown to be a practical certainty--makes
provision for those crimes by maintaining a police, reform schools,
prisons, and armies. The Governor of the universe, knowing the liability
of man to sin and fall--a liability which by his foreknowledge was to him
a certainty--made provision for that foreseen apostasy. He made provision,
both by the creation of a world suited to a sinful race kept under a
probation of mercy, and by appointing a Redeemer, the 'Lamb of God,'
slain, in the eternal purpose, before the foundation of the world. If Mr.
Hume's objection has force at all, it has force against every wise
provision of God to meet the consequences of man's foreseen wickedness. It
is wise, forsooth, on man's part, to foresee coming evil and prepare for
it; but if God do this, men count it worse than folly: they declare it to
be an endorsement of the evil! So foolishly do men reason about the high
things of God! My answer to Mr. Hume, then, has four parts:

"1. The existence of unexplainable difficulties does not disprove the
truth and reality of any fact or principle.

"2. The supposition that God made provision for the present apostasy of
the human race is burdened with fewer and smaller difficulties than its
denial.

"3. The word of God declares that he did make provision for the fall of
man by the pre-appointment of a Redeemer.

"4. That style of reasoning which seeks to justify or palliate man's first
sin because God prepared this world for a fallen race would palliate and
justify all wickedness, because the sins of men are woven into every
figure of the web of divine providence. Not the treason of Judas alone,
but the whole sum of man's evil-doing, is embraced in the far-reaching
plan of God. How this magnifies the wisdom of God! He binds together in
one bundle his own righteousness and the sins of men, in a most intricate
interlacing, yet without blending the two and without staining the glory
of his holiness.

"I hope I have made this plain. Do you think, Ansel, that you can repeat
the substance of this answer to Mr. Hume?"

"I will try, sir, if he asks."

"You will all notice," added Mr. Wilton, "that I have not denied that
there is a deep mystery in this preparation for the sins of men not yet
created, and that I have not attempted to explain this mystery. I have
only tried to show that the admission of the view I have given you is more
satisfactory to reason than its denial, and that the mysteries of this
view are not unreasonable and self-contradictory, for the greatest
mysteries are often the most reasonable things in the world.

"My introduction has become much longer than I designed, but now let us
turn our attention to the subject of the lesson.

"To aid us in understanding God's wise arrangements in the management of
heat, we need, first, to consider what heat is and to review the laws of
its action. Without this, we could look on and wonder at God's working in
nature, but could not explain that which we saw.

"Ansel, will you state the theories which have been held touching the
nature of heat?"

"I will do it as well as I can. The ancient philosophers supposed fire to
be one of the four elements of which all bodies were composed. The three
other elements were earth, air, and water. These four elements were
mingled in various proportions. Of these, fire was esteemed the purest and
most ethereal; this constantly tended upward to the empyrean, the highest
heaven, where the element of fire and light was supposed to exist
unmingled and pure. In the seventeenth century, Beccher and Stahl, two
German chemists, brought forward what is known as the _phlogistic
hypothesis_. They supposed that every combustible body held in
composition a pure, ethereal substance which they called _phlogiston_, a
Greek word which signifies _burned_, and that in combustion this
phlogiston escaped. Flame was supposed to be this escaping phlogiston.
These were the notions held about fire and combustion, but they are hardly
worthy to be called theories of heat. The discovery of oxygen by Dr.
Priestley of England, in 1774, and the introduction of the balance by
Lavoisier of France, joined with the ever-enlarging circle of facts to be
explained, rendered the phlogistic hypothesis untenable, and it was thrown
aside.

"Until a few years since the _caloric_ theory was generally received.
According to this theory, heat is a _substance_, a subtle ether, diffused
through all bodies and surrounding their atoms. This ether has been
supposed to have a strong attraction for the atoms of every other
substance, while between its own atoms a strong repulsion exists. In solid
bodies each atom of matter, or in compound bodies each cluster of atoms,
has been supposed to be surrounded by a little atmosphere, so to speak, of
caloric, which prevented the atoms from coming into absolute contact.
According to this theory, heat expands bodies by increasing and deepening
these minute atmospheres, thus pressing the atoms farther from each
other."

"You need not explain this theory farther," said Mr. Wilton; "we have
hardly time to go into the history of theories. Tell us the latest
received theory."

"The theory now commonly believed is called the _mechanical_ or _dynamic_
theory. According to this theory, the essence of heat is _motion_. A hot
body is one whose atoms are in a state of rapid and intense motion or
vibration; and the sensation of heat on touching a hot body arises from
the impact, or rapid blows, of the agitated atoms, communicating the same
atomic vibration to the flesh and nerves of the hand."

"Very well stated, Ansel. This is the theory now more commonly received.
The caloric theory, like the crude notions of the old Greek philosophers
about fire, and like the phlogistic hypothesis, has been rejected because
it failed to explain the phenomena of heat. Whether the dynamic theory is
destined to share the same fate remains to be seen. It seems, however, to
have a better foundation than its predecessors. The dynamic theory,
though recently made popular, is by no means a recent conception. It was
advocated by such men as Bacon, Newton, Rumford, Davy, Locke, and others.
Locke, the distinguished intellectual philosopher who lived in the latter
half of the seventeenth century (born 1632, died 1704), said, 'Heat is a
very brisk agitation of the insensible parts of an object, which produces
in us that sensation from which we denominate the object hot, so that what
in our sensations is heat in the object is nothing but motion.' Benjamin
Thompson, an American gentleman who went to Europe in the time of our
revolution, and for his scientific fame was made Count Rumford, and became
the founder of the Royal Institution of England, declared that he could
form no conception of the nature of heat generated by friction unless it
were motion.

"A beautiful generalization has been made to show how well this idea of
heat harmonizes with the entire plan of the universe. In the whole
boundless universe each system of worlds, like our solar system, may be
regarded as a molecule, or complex atom. These cosmical molecules, or
complex atoms of the universe, are in motion through unmeasured space. In
these systems of worlds the planets, with their satellites, are the
molecules, and they are in motion--indeed, they commonly have several
motions. Our earth, for example, rotates upon its axis once each day; it
revolves in its orbit around the sun once each year, and the axis of the
earth has a slow wabbling motion which produces the precession of the
equinoxes, requiring 25,868 years for a complete revolution. The earth
also is made up of parts, and all these are in ceaseless motion. As said
the old Greek philosopher, 'All things flow'--that is, everything is in a
state of change. Solomon has well described this perpetual movement and
change: 'One generation passeth away, and another generation cometh. The
sun also ariseth, and the sun goeth down, and hasteth to his place whence
he arose. The wind goeth toward the south, and turneth about unto the
north. It whirleth about continually, and the wind returneth according to
his circuits. All the rivers run into the sea; yet the sea is not full;
unto the place from whence the rivers come, thither do they return again.
All things are full of labor; man cannot utter it. The eye is not
satisfied with seeing, nor the ear filled with hearing. The thing that
hath been, it is that which shall be; and that which is done is that which
shall be done, and there is no new thing under the sun.' Eccles. i. 4-9.
It is certainly in harmony with this universal movement that the atoms of
matter, though they seem so closely packed, should in their inconceivable
smallness through inconceivably minute spaces vibrate, or rotate, or
revolve through an orbit, never at rest. Intensity of heat we may think of
as intensity of this atomic motion--a wider swing, so to speak, in their
vibration or revolution. This, of course, requires a wider separation of
the atoms and a consequent expansion of bodies. A feebler atomic motion
permits the atoms to approach each other. In this manner we explain the
enlargement of bodies by heat and their contraction by decrease of
temperature. 'The ideas of the best-informed philosophers are as yet
uncertain regarding the exact nature of the motion of heat, but the great
point at present is to regard it as a motion of some kind, leaving its
more precise character to be dealt with in future investigation.' This is
the most we can do at present."

"What is the evidence," asked Samuel, "that the dynamic theory of heat is
true?"

"The evidence that any theory is true is its ability to explain the facts
or phenomena with which it has to do. If it explains all the facts and
contradicts no known principles, it is regarded as true, or at least no
objection can be made to it. Let me illustrate. Astronomers had long
inquired what force or law controlled the movements of the heavenly
bodies. At length Newton answered, A force of attraction between bodies
which decreases in proportion as the square of the distance between them
increases. This explanation has been found sufficient to explain all the
known facts in the working of the heavenly bodies. Upon the basis of this
theory astronomers calculate the positions of planets and comets for years
and centuries to come.

"This theory led to the discovery of the planet Neptune, the last
discovered of the primary planets. For thirty years irregularities in the
motion of Uranus had been noticed. These variations were so slight that if
another planet had revolved in the proper orbit of Uranus they would have
seemed to the naked eye, throughout their course, one and the same star.
This slight irregularity of motion was so nicely measured that the place
of the unseen planet which caused it was almost exactly calculated from
the estimated force and direction of its attraction. This theory of a
universal attraction of gravitation so well explains all the facts in the
case, and has become so universally received, that we are liable to forget
that, after all, it is nothing but a theory.

"Our idea of the structure of the solar system was at first only a theory.
The astronomer does not see the planets revolving in regular circles
through the heavens and moving around the sun. He only sees the shining
points moving back and forth upon the concave vault, doubling and crossing
their tracks apparently in the greatest disorder. How shall their motions
be explained? Astronomers have found that the motions of planets revolving
around a central sun, when seen from one of the planets, must present just
these apparent irregularities. This explanation is so full and complete
that it is now counted not a theory, but an established fact. The same may
be said of the shape of the earth.

"The dynamic theory of heat explains the phenomena of heat better than
any other explanation that has been proposed. It explains the radiation of
heat from the sun or from any other hot body: vibrations or impulses are
propagated through that ether which is supposed to fill all space. It
explains the conduction of heat through solid bodies in the same manner.
It explains the expansion of bodies: the atomic motion forces the atoms of
bodies farther apart. It explains the production of heat by friction or
collision, which no other theory is able to do: the shock of the collision
generates this atomic vibration. It explains the production of heat by
combustion: the atoms of oxygen and carbon or hydrogen dash against each
other and generate heat by the collision. This theory explains the
transmutation of motion, or living force, and electricity, into heat, and
the transmutation of heat into electric or mechanical force. These points
will come up again, and I now only refer to them in answering Samuel's
question. The dynamic theory explains the phenomena of heat and its
relations to force, light, and electricity exceedingly well, and for this
reason men look upon it with favor and count it as probably true. If in
the progress of scientific investigation it shall be found to explain all
the new facts discovered and meet well all the demands made upon it, it
will at length be received as an admitted principle in physical science.
The _wave_ theory of light and the _vibratory_ theory of sound may be
looked upon as thus established.

"At our next lesson we shall take a rapid review of the effects and laws
of heat."



CHAPTER IV.

HEAT A GIFT OF GOD.


The class is again promptly in place and ready for work.

"As I announced a week ago," said Mr. Wilton, "we will to-day take a rapid
review of the effects and laws of heat. Will you tell us, Peter, the first
and chief of these effects?"

"Yes, sir: combustion."

"What is combustion?"

"Commonly the rapid union of oxygen with some combustible substance,
attended with the evolution of heat."

"Was your answer correct, then?"

"No, sir," said Peter, blushing; "I spoke before I thought."

"Will you correct your answer?"

"The first and chief effect of heat is expansion."

"That is right. Our sensation of heat is of course only a
_sensation_--merely the _feeling_ which results from the effects of heat
upon our nerves--but the chief physical effect of heat is the expansion of
bodies. The chemical qualities of bodies are not changed: they are not
made either heavier or lighter. A sufficiently high temperature renders
bodies luminous, and then we call them red hot or white hot. Solid bodies
begin to be luminous at a temperature of about one thousand degrees. But
the one invariable effect of heat, with two or three apparent exceptions,
is expansion. You may mention, Samuel, some familiar illustrations of the
effect of heat in expanding bodies."

"The blacksmith heats the wagon-tire in order that it may easily slip over
the wheel. If a kettle be filled with cold water, by heating it the water
is expanded and runs over. I have noticed that the spaces between the ends
of the successive iron rails upon the railroad are larger in winter than
in summer, showing that the rails are shorter in winter than in summer.
While skating during the cold winter evenings upon the mill-pond, I have
seen cracks in the thick ice start and run across the mill-pond with a
roar almost like thunder. The ice was contracted by the cold till it
could no longer fill the whole space between the banks, and being frozen
fast to the banks, it was torn asunder. The mercury in the tube of a
thermometer is constantly expanding or contracting by every change of
temperature."

"Yes, those are all good illustrations, and we might go on to mention
others equally good by the score. In cold countries, during the intense
cold of winter, the surface of the earth cracks by shrinkage, just as you
have seen the ice upon the mill-pond torn in two. The Britannia iron
tubular bridge over the St. Lawrence at Montreal rises and falls two and
one-half inches on account of greater expansion of the upper surface when
exposed to the heat of the sun, while a loaded freight train causes a
depression of but one-fourth of an inch. A few years since, in order to
make some philosophical experiments connected with the rotation of the
earth upon its axis, a ball was suspended by a wire in the interior of
Bunker Hill monument. By this means it was accidentally discovered that
the heat of the sun, expanding the sides of the monument exposed to its
rays, caused the whole monument to sway back and forth daily."

Here Ansel raised his hand.

"What is it, Ansel?"

"I was going to mention the belief of geologists that the mountain ranges
were thrown up by the contracting of the earth's crust on account of
cooling."

"That is an illustration of contraction by loss of heat on an enormous
scale. The materials which form our globe may have existed in the
beginning in a nebulous or gaseous state. There is certainly very good
reason for believing that the earth was once in a fluid state, the whole
of its substance molten by intense heat. It is certain that the interior
is now hot, and portions of it molten. It is by very many believed that
the whole interior is molten. The crust of the earth may have been formed
by cooling. If after an outer crust had been formed, and its temperature
had fallen so low as to become nearly stationary, the interior mass
continued to cool, the molten mass would tend to sink away from the crust
and the crust would sink in upon it by wrinkling. Thus mountains may have
been formed. Along the line of fracture the easiest vents would be formed
for volcanoes. But this carries us somewhat aside from our subject, and
as the expansion of bodies by heat has been sufficiently illustrated, we
will leave it. Will some one now state the manner in which the dynamic
theory of heat explains this expansion?"

Samuel answered: "I think you have already given us the explanation."

"I have briefly referred to it, but you may give it again."

"The atomic motion which is supposed to constitute what we call heat,
whatever that motion be, whether a vibration or rotation or revolution,
requires that the atoms of bodies shall not be packed in absolute contact,
and the more intense the agitation or the wider the swing of the vibration
or revolution, the greater must be their separation. Hence heat expands
bodies by thrusting their atoms farther apart."

"That will do," said Mr. Wilton. "Let us look now at some of the secondary
effects of heat. You may mention some of them, Ansel."

"Heat relaxes or overpowers the cohesive attraction of bodies."

"What is cohesive attraction?"

"It is that force which binds together the atoms of matter in simple
substances, that is, bodies like iron or copper or silver, composed of but
one kind of substance, or in compound bodies it is the force which unites
the compound molecules of matter."

"Give us now some illustrations of the effect of heat in overcoming
cohesive attraction."

"The blacksmith heats his iron in order to overcome its cohesive
attraction and render it soft, that he may easily hammer it. The founder
heats his metal till its cohesion is so far destroyed that it becomes
fluid and can be poured into the mould. Heat relaxes the cohesive force of
ice and changes it to water, and by farther heating its cohesion is
entirely overcome and the water is changed to a gas."

"We use heat also in cooking our food," spoke up Peter: "is it not because
heat destroys the cohesive attraction, and thus softens it?"

"If that were the only effect of heat upon food," said Mr. Wilton, "we
should be obliged to eat our food hot, for as soon as it cooled the
cohesion would return and the food would be raw again. The operation of
heat in cooking is various, and part of the effect is commonly to be
ascribed to the water in which the food is cooked or to that which is
contained in it. By the combined agency of heat and water starch swells to
twenty or thirty times its original bulk and the minute starch grains
burst open. In cooking potatoes the starch of the potato absorbs a portion
of the water that is in it, and thus renders it dry and mealy. The action
of heat and water upon rice, wheat, and other grains is similar to their
operation upon starch. In the baking of bread the starch is converted into
gum. In boiling flesh the effect is partly due to the solvent powers of
water: the juices of the flesh are extracted, the gelatin is dissolved,
the fat is liquefied, and the cells in which the fatty matter is held more
or less burst, the albumen is solidified, and by long boiling the texture
and fibre of the flesh are destroyed. The albumen of an egg, that is, the
white, coagulates by heat. But in most of these processes the action of
heat cannot be separated from that of water.

"But there is another effect of heat very important both in nature and in
the arts. What is that?"

"The quickening of chemical affinity," answered Samuel.

"That is right: heat is necessary for the operation of chemical affinity.
Perhaps this is only a weakening of the cohesive force, thus allowing the
chemical attractions to assert their strength. But the fact is that, while
in many cases the chemical affinities act with great energy at ordinary
temperatures, in other cases they slumber, however closely the substances
are brought into contact, till their temperature is raised. Samuel, you
may mention some illustrations of this principle."

"A few months ago I visited Hazard's powder mills, in Enfield,
Connecticut, and there learned how gunpowder is made. The charcoal, the
sulphur, and the nitre are first finely pulverized, then ground together
for hours till thoroughly mixed, and afterward pressed together. This mass
is then broken into grains and the grains polished. But though these
elements are brought into so close contact, yet they do not combine and
explode till heat is applied. The same is true of the combustion of wood
and coal. The carbon and the hydrogen of the fuel are constantly
surrounded with the oxygen of the air, but they do not take fire and burn,
that is, they do not combine with the oxygen, till they are raised to a
red heat, or perhaps even to a higher temperature. If a stove filled with
burning coal be cooled down to a low temperature by applying ice, the
combustion will cease, the fire will go out. Our teacher at the academy on
one occasion heated a steel watch-spring red hot and plunged it into a jar
of oxygen, and the steel spring began quickly to burn with great fury."

"You have given us good illustrations, Samuel, and that which is true of
carbon and hydrogen and oxygen is true of substances in general. The
effect of heat in producing chemical changes is very important everywhere.
It is seen not only in the chemist's laboratory and in the artisan's shop,
but also in the laboratory of Nature. Plant a grain of corn in midwinter:
why does it not germinate and grow? Nothing is needed but the requisite
heat to quicken the chemical affinities into action. Earth and air furnish
the needed material for the growth of forest trees in winter as well as in
summer, but the cold holds in check the chemical forces and prevents the
requisite chemical combinations. No sooner does the sun quicken that
atomic vibration or revolution which we call heat than vegetable growth
begins. Heat is necessary for those chemical changes by which food is
digested in the stomach and the processes of nutrition carried on in every
part of the body. If a man finish his dinner with ice cream or ice water,
the process of digestion is delayed till the contents of the stomach
recover their proper temperature. This is one chief reason why warm,
comfortable clothing is so very important, especially for children. All
the vital processes are chemical processes: they are carried on through
chemical affinities. Unless the body be kept at a suitable temperature,
these processes are feeble and imperfect, nutrition and vital combustion
are hindered, and diseases are engendered.

"These, then, are the chief effects of heat. It expands bodies, weakens
cohesive attraction, and quickens the chemical affinities into activity."

Ansel again raised his hand.

"What do you wish?"

"Will you please tell us, Mr. Wilton, how this weakening of cohesive
attraction is explained upon the dynamic theory of heat?"

"I will do so with pleasure. The increased atomic motion in the heated
body throws the atoms farther apart, as we have already learned, and by
this increase of distance their attraction is diminished. If the earth
were twice its present distance from the sun, their attraction for each
other would be four times less than it now is; if its distance were three
times as great, their attraction for each other would be nine times less.
The attraction of gravitation diminishes in proportion as the square of
the distance through which it must act increases. Perhaps cohesive
attraction diminishes according to the same law, though the spaces are so
small that this cannot be demonstrated, but it is certainly weakened by
the expansion of bodies through the agency of heat."

Here Peter raised his hand.

"What will you say, Peter?"

"Do not men heat and burn bricks, not to soften them, but to harden them?"

"That is true," said Mr. Wilton; "but in this there is a process of drying
as well as of heating, and the hardening is due chiefly to the complete
drying by the intense heat. Too great heat will melt bricks while in the
process of burning. I once heard a brick-burner say that he could melt the
brick around the arches in his kiln in half an hour, if he pleased to put
in fuel and let the fire burn. Indeed, almost every known solid substance
has been fused by heat. Whether carbon has ever been melted is an
unsettled question."

"I would like to inquire," said Samuel, "why water will not burn. Is it
because it evaporates before it reaches a sufficiently high temperature?"

"This is a little aside from our subject, but the incombustibility of
water is a provision of the Creator so very important that we will stop to
notice it. I think, however, that by a little thought you yourself can
answer the question. Tell me again what combustion is."

"Combustion is commonly the combining of oxygen with some other substance
called a combustible. The rusting of iron and the decay of organic bodies
are forms of slow combustion."

"Now tell us the composition of water."

"Water is composed of oxygen and hydrogen--eight parts of oxygen to one of
hydrogen, by weight, or two parts of hydrogen to one of oxygen, by
measure."

"How is water formed from these two gases? Are they mixed together as
oxygen and nitrogen are mingled in the air, or are they chemically
united?"

"They are chemically united: they are burned together. When hydrogen
burns, the product is water."

"Water is then a _product_ of _combustion_. Can you not now tell why water
is incombustible?"

"I think I now see the reason. The oxygen, being itself the supporter of
combustion, will not burn, and the hydrogen has been already once burned
in the formation of water."

"And that which is true of water is true, in a greater or less degree, of
other products of combustion. The burning of charcoal produces carbonic
acid, and carbonic acid will not burn because it is the production of
combustion. A candle is extinguished by it as quickly as by water. By a
recent invention carbonic acid is used to extinguish conflagrations. The
carbon has once united with oxygen, and a second combination with an
additional amount, or, as a chemist would say, with another equivalent, of
oxygen is much more difficult."

"I think," said Samuel, "I now understand why water will not burn, but
will you please also to tell us why water puts out fire better than
almost anything else?"

"In order to extinguish fire one of two things must be done: either the
supply of oxygen must be cut off or the combustible must be cooled down to
a temperature below the burning point, when the combustion will cease of
itself. When we shut the draught of an air-tight stove, we check the
combustion by shutting off the full supply of oxygen. If we could wholly
prevent the access of oxygen to the fuel, the fire would at once be
extinguished. If oxygen should then be admitted again before the fuel had
cooled down below the burning point, combustion would at once begin again.
A blazing brand is extinguished by being thrust into ashes, because it is
shut away from oxygen. In the same way we extinguish the flame of a candle
with a tin extinguisher. On the other hand, fires often go out because the
necessary temperature is not maintained. Water puts out fire in both these
ways, but especially by the second. Water poured in torrents from a fire
engine upon a fire forms a film of water, and the burning material shuts
out the oxygen. But the water acts chiefly by lowering the temperature.
No other known substance except hydrogen gas requires so much heat to
raise it through a given number of degrees of temperature as water. As
much heat is required to heat one pound of water as thirty pounds of
mercury. Hence, water poured upon burning timber cools it to so low a
temperature that it ceases to burn.

"In addition to this, we may notice that wood saturated with water cannot
be heated above the boiling point of water till the water is evaporated.
As fast as the wood and the water rise or tend to rise above two hundred
and twelve degrees, the water changes into steam and carries away the
additional heat. The consumption of heat in the formation of vapor we must
look at more carefully in a future lesson. We will suppose that a house is
in flames. A fire engine throws a stream of cold water into the midst of
the conflagration. The cold water, dashing against the burning wood, cools
the heated surface; it is absorbed into the pores of the wood and hinders
its rapid heating; a portion of the water, being changed into steam,
carries off the heat; the steam, mingling with the flame, lowers the
temperature of the burning gas, and in proportion as steam fills the
surrounding space oxygen is driven away. A burning coal mine in England
was once extinguished by forcing steam into it, thus driving out the air
which supported the combustion and cooling down the burning coal.

"The advantages which men receive from these agencies of heat are so
manifest that we cannot help noticing them. I do not refer to the comfort
of a pleasant temperature, nor the impossibility of living in a
temperature extremely low, but to all those processes by which man subdues
nature, provides for himself food, clothing, and dwelling-places, and
builds up civilization. Heat is that force which enables man to accomplish
his ends. Heat brings the iron from the native ore, and heat renders it
malleable and plastic to be shaped for man's uses. Heat quickens the
chemical affinities and renders the arts of civilized life a possibility.
Heat brings together oxygen and carbon in ten thousand furnaces, and the
heat engendered by the combustion, changed to force, drives the ponderous
or nimble machinery which carries on the work of the world. Heat quickens
the chemical affinities and causes the wheat to grow; heat prepares the
wheat for man's food; and by the aid of heat that food is changed in
man's body, nutrition goes on, the body is built up, waste matter is
removed, and all the vital processes are supported. Without these agencies
of heat--softening and subduing stubborn matter on the one side, and
quickening its forces on the other--man could not exist.

"Let me remind you that these agencies of heat are of God's devising. If
the operations of heat are beneficent to man, it is because God wished to
bless his creatures. I am not much given to moralizing, but when I see how
completely these simple effects of heat meet man's wants, I cannot help
remembering and admiring the wisdom of the great Designer. It is _God_ and
not blind, unconscious Nature that is working."

"This reminds me," said Samuel, "of the tradition in Greek mythology that
Prometheus stole fire from Jupiter and brought it down to man in a reed as
a precious treasure. It seems to me like a gift from heaven."

"This mythological tradition has, however, one falsehood: there was no
need that men should steal fire from the gods; God freely gave it. Heat is
indeed a gift from heaven."



CHAPTER V.

CONVEYANCE AND VARIETIES OF HEAT.


"To-day we review the modes in which heat passes or is conveyed from place
to place. It is evident that if heat were confined to the very place or
point where it is generated, it could subserve none of those uses to which
it is now applied in the economy of Nature or in the works and arts of
man. But heat passes from place to place with great facility, and by one
method, with the speed of light, it tends to diffuse itself evenly through
all; it seeks an equilibrium. The modes of its diffusion, or conveyance,
are three in number. Ansel may name them."

"Heat passes from place to place and from body to body by 'conduction,' by
'radiation,' and by 'convection.'"

"What is meant, Ansel, by the 'conduction' of heat?"

"The passing of heat from atom to atom and from particle to particle
through a body is called conduction."

"That is right. I will call upon Peter to give some illustrations of the
conduction of heat."

"The examples are so many," Peter answered, "that I hardly know what to
mention first. If I hold a pin in the flame of a lamp, the part of the pin
that touches the flame is first heated, but soon the heat runs along the
whole length of the pin and burns my fingers. The parts of a stove which
touch the fire are first heated, and from them the heat spreads through
the whole stove. A pine-wood shaving, kindled at one end, is heated by
conduction, but the heat passes through it very little faster than the
flame follows. Heat escapes from our bodies by being slowly conducted
through our clothing. There is no end to the examples of conduction which
one might give."

"We must not think of the conduction of heat," said Mr. Wilton, "as if it
were a fluid slowly absorbed by a porous body, as water poured upon the
ground soaks into it, or as water percolates through a lump of sugar and
moistens the whole of it. We must remember that the transfer of heat is
not a transfer of any substance, but a transfer of motion. One atom is set
in motion, and strikes against another atom and sets that in motion, and
thus motion is communicated from atom to atom and from molecule to
molecule through the whole mass of matter till every atom is agitated with
the heat vibrations. Do all bodies conduct heat with equal rapidity?"

"No, sir," replied Ansel; "there is the greatest possible difference. Some
substances are called good conductors, because heat permeates them so
readily and rapidly; others conduct heat very slowly, and are called poor
conductors or bad conductors."

"That is right. Every child soon learns by experience to make a practical
distinction of this kind. He very soon understands that he can hold a
stick of wood without burning his hand, even though it be blazing at the
other end, but that when a piece of iron is red hot at one end he must not
take hold of it at the other. The child very soon learns to know the
different feeling of a cotton night-gown from one of flannel, and the
difference in apparent warmth between a linen pillow-case and a woolen
blanket. After a room has been heated for a considerable time the various
objects in it all become of the same temperature, and the same is true in
a cold room; but how great the difference in the sensations produced by
touching the oil-cloth and a woolen carpet in a cold room! Good conductors
of heat, if hot, feel very hot; or if cold, feel very cold; while poor
conductors make a much less decided impression. Why is this, Samuel?"

"The good conductors receive heat or part with it very readily. If the
good conductor be hotter than our bodies, it imparts its heat rapidly to
our hand, and because we receive heat rapidly from it, it feels to us very
hot. Or if it be colder than our bodies, it takes heat from our hands very
rapidly, and gives the impression of being very cold. Poor conductors
impart heat to the skin or take it away more slowly, and hence feel as if
their temperature were more nearly like that of the body."

"The conducting qualities of bodies," said Mr. Wilton, "seem to depend
chiefly upon their structure or the arrangement of their atoms. Bodies
which are compact and solid in their structure convey heat more rapidly
than those which are loose and porous. Hence solids are better conductors
than fluids, and fluids are better conductors than gases, and among solids
the metals are better conductors than organized bodies, like wood or
flesh, and better than the loose and porous minerals. In bodies of loose,
porous, or fibrous texture, the continuity of the conductory substance is
constantly broken. The particles in a mass of sawdust touch only at a few
points, leaving frequent spaces. In woolen and cotton fabrics the points
of junction of the fibres are very few, comparatively. For this reason the
motion is not readily communicated from atom to atom.

"The crystalline arrangement of atoms has an influence upon conduction of
heat. Heat is conducted more rapidly in a direction parallel with the axis
of crystallization than across that axis. Wood conducts heat more rapidly
in the direction of the grain. This arrangement seems to be well adapted
for keeping trees warm in winter. Their roots reach down into the earth,
which remains warm in the coldest weather. This heat of the earth travels
along the fibres up through the tree, while the heat conducted across the
fibres escapes much more slowly into the open air. The bark also, being a
very bad conductor, hinders the escape of heat. Of metals, silver is the
best conductor. I will give you a brief table which will show the great
difference in the conducting qualities of some of the metals. Counting the
conducting qualities of silver as 100, the table is: 'Silver, 100; Gold,
53; Copper, 74; Iron, 12; Platinum, 8; German Silver, 6; Bismuth,
2.'--_Youmans._

"What is the second method by which heat passes from place to place?"

"It is radiated," replied Ansel.

"And what is radiation?"

"It is motion in straight lines or rays diverging from a centre. From a
hot body heat is passing off in straight lines in every direction. As a
lamp radiates light, so does a hot body radiate heat."

"Radiant heat," said Mr. Wilton, "moves with the same velocity as light,
that is, one hundred and ninety-two thousand miles per second. It also
follows the same general principles as light in all its motions. It is
absorbed, reflected, or transmitted in the same manner as light. And this
is true of either luminous heat--that is, heat radiated from a body which
is red hot--or obscure, or dark heat.

"As there are good and poor conductors, so there are good and bad
radiators of heat. The radiation of heat depends upon three conditions:

"1. Upon the temperature of the body. The higher the temperature, the more
rapid and energetic is its radiation.

"2. Upon the surface of the radiating body. A dull, rough surface radiates
heat more rapidly than a surface bright and polished.

"3. Upon the substance of the radiating surface. With surfaces equally
smooth and bright, some substances radiate heat much better than others. A
surface of varnish radiates heat much more powerfully than a surface of
gold or silver.

"Ansel, you may, if you can, explain the radiation of heat."

"I can give no other explanation than that radiation is conduction through
that subtle ether which is supposed to pervade all space."

"Very well; perhaps that is as good an explanation as can be given. But it
seems rather like the propagation of an impulse than the spreading of
atomic vibrations in every direction. The motion is propagated in
straight lines. If it be conduction, it must be carried on by different
vibrations from those of ponderable substances. Heat, light, and
electricity are supposed to be all propagated through the same theoretical
ether. Sir Isaac Newton estimated the density of the ether as seventy
thousand times less than the density of our atmosphere, and its elasticity
in proportion to its density as four hundred and ninety millions times
greater. But the very existence of this universally-diffused ether is a
supposition made to account for the phenomena of light, heat, and
electricity; and, of course, all its qualities must be theoretical also.
Radiation is believed to be the propagation of a motion or impulse through
an inconceivably rare and elastic ether.

"Peter, what is the third method by which heat passes from place to
place?"

"Convection," was his reply.

"What is meant by convection of heat?"

"The conveyance of heat by carrying a heated body. If I remove a hot iron
or a kettle of hot water, I must of course carry the heat which it
contains."

"A very good illustration of the convection of heat," said Mr. Wilton,
"is seen in the common method of heating water. The heat is applied at the
bottom of the vessel containing the water; as fast as the water at the
bottom next the fire is heated, it rises and carries the heat to the top;
cold water comes to take its place, and this in turn is heated and rises
and carries heat to the top. This process is carried on till all the water
comes to the same temperature. Thus water is heated by convection of heat.

"A grander illustration is seen in winds and ocean currents. Warm winds
carry heat enough to warm a continent, and the mighty ocean currents are
still more efficient in transferring heat from one part of the earth to
another.

"Another point we need to understand. When radiant heat falls upon a body,
what becomes of it?"

"It is disposed of," answered Samuel, "in one of three ways: it may be
reflected according to the same principles by which light is reflected; or
it may be transmitted, that is, pass through the body; or it may be
absorbed, that is, stop in it."

"Very well stated, Samuel. In regard to reflection I need to say very
little. You know how light is reflected from a polished surface, such as
a lamp reflector: heat is reflected in the same manner. One fact you must
bear in mind touching reflected heat: it does not heat the reflecting
body.

"There is no need of telling you that light passes through certain
substances. It passes through gases and through some liquids and some
solids. The best of glass, though it is so solid, interposes very little
hindrance to the passage of light. Heat in like manner radiates through
certain solids. Luminous heat is radiated through glass. Rock-salt
transmits dark heat also. A plate of alum permits light to pass, but stops
both luminous heat and dark heat. Remember that transmitted heat, as was
said of reflected heat, does not heat the body through which it passes. I
have seen boys make burning-glasses of ice. The heat passes through them
and burns that upon which it is concentrated, while the ice itself through
which the heat passes is not melted.

"If a body have a good radiating surface, that is, if its surface be dull
and rough, the heat which falls upon it will be mostly absorbed. The
reflecting and absorbing qualities hold an inverse ratio to each other;
the better the reflecting qualities, the worse the absorbing, and the
worse the reflecting, the better the absorbing. Heat which is absorbed by
a body commonly raises its temperature, and remains in the body till it is
slowly radiated or is conducted away by the air or other bodies which come
in contact with it.

"What is that heat called, Ansel, which is absorbed by a body with no rise
of temperature?"

"It is called _latent_ heat."

"That is the old and common expression, but what is meant by latent heat?"

"The word _latent_ signifies _lying hidden_ or _concealed_. Latent heat,
as you suggested in your first question, is that heat which a body
receives without showing it by a change of temperature."

"That name 'latent heat,'" said Mr. Wilton, "expresses the opinion of
those who invented it; they supposed that heat was in some manner hidden
in certain bodies. We must not suppose, however, that this latent heat
continues to exist in bodies as heat; latent heat is that heat which is
converted into force or some other motion than the atomic heat vibrations,
and is employed otherwise than in raising the temperature. You will
understand this best by an illustration.

"Take one hundred pounds of ice at the temperature of thirty-two degrees,
that is, as warm as is possible without melting. That one hundred pounds
of ice will absorb heat which would raise one hundred pounds of ice water
through one hundred and forty degrees, and by receiving that heat it is
melted, but the water produced has the temperature of thirty-two degrees.
It has received one hundred and forty degrees of heat, but its temperature
is not raised a single degree. This one hundred and forty degrees of heat
has been transmuted into force and employed in overcoming the crystalline
attraction of the atoms of water.

"Let that ice water at thirty-two degrees of temperature receive one
hundred and eighty degrees of heat, and the water rises to two hundred and
twelve degrees, the temperature of boiling. But whatever additional heat
is absorbed brings no increase of temperature, but transforms the water
into steam. It is employed in overcoming the cohesive attraction of the
molecules of water and changing the liquid to a gas. About one thousand
degrees of heat is thus expended, but the steam which is produced has
only the temperature of two hundred and twelve degrees. If the process be
reversed, the steam gives up, as it is said, the one thousand degrees of
heat in returning to the condition of water and the one hundred and forty
degrees in resuming the crystalline structure of ice. The heat which was
employed as force in overcoming the atomic and molecular attractions is
transmuted again to heat, and shows itself in raising the temperature. And
that which is true of water is true of any other substance in changing its
form from a solid to a liquid or from a liquid to a gas, or the opposite.
In an amount different for each kind of matter, in all these changes of
condition, heat is transmuted to force or force to heat.

"These transmutations are going on ceaselessly in the operations of
Nature, and without understanding them we cannot appreciate the wonderful
operations of heat in the world. The heat of the sun beams upon the ocean;
the greater part of that heat is expended as force in overcoming the
molecular attraction of water, thus converting it to vapor, and in raising
that vapor to the higher regions of the atmosphere. This heat-force, or,
as we might call it, 'sunpower,' expended upon the earth, amounts to
thousands of millions of horse-power daily.


[Illustration: TRANSMUTATION of HEAT.

Page 113.]


"Examples of the transmutation of force into heat abound everywhere. A boy
strikes his heel upon the stone pavement; from the point of contact
between the stone and the steel points in his boot heel sparks of fire fly
out. Force is changed to heat so intense that particles of steel are set
on fire. Savages who have no better methods of kindling fire rub dry wood
together till the sticks ignite. The force expended in overcoming the
friction is changed to heat. In the combustion of coal beneath the steam
boiler we see both processes going on. The atoms of carbon dash against
the atoms of oxygen, and the force of the collision generates the heat of
the combustion. This heat, born thus of force, is again transmuted to
force, and drives the engine and the machinery attached. In our study of
God's management of heat we shall constantly meet with these changes. You
will need, therefore, to study carefully this subject of latent heat.

"Dr. Joule, of Manchester, England, has discovered the ratio between heat
and force, that is, the amount of force which by transmutation produces
any given amount of heat. The force of a one-pound weight which has fallen
one foot is taken as the unit of force, and the amount of heat which is
required to raise one pound of water one degree is taken as the unit of
heat. By many and various careful experiments, Dr. Joule demonstrated that
772 units of force are the equivalent of one unit of heat. A pound weight
falling 772 feet, or 772 pounds falling one foot, and then arrested,
produces heat sufficient to raise one pound of water one degree. The
result is the same whatever the method by which the force is expended. If
water be agitated or shaken, if sticks of wood or iron plates be rubbed
together, if an anvil be struck with a hammer, or if a bar of iron or
copper be moved back and forth between the poles of an electromagnet, the
force expended is changed to heat. You must remember, however, that force
becomes heat only so far as the force is actually expended, or used up so
that it no longer exists as force.

"These conclusions are supported by other beautiful experiments. 'An
electric current which, by resistance in passing through an imperfect
conductor, produces heat sufficient to raise one pound of water one
degree, sets free an amount of hydrogen which, when burned, raises exactly
one pound of water one degree. Again, the same amount of electricity will
produce an attractive magnetic force by which a weight of 772 pounds may
be raised one foot high.'--_Youmans._ We conclude from experiments like
these that heat, mechanical force, and electricity are interchangeable
forces; they may be transmuted the one into another.

"By this principle of the transmutation of heat and mechanical force we
explain the production of heat by compression and the loss of heat by
expansion. Samuel, you may state the fact upon this point."

"If any substance be suddenly compressed," answered Samuel, "heat appears;
if it be expanded, cold is produced. Since gases expand or yield to
pressure so readily, they furnish the best illustration of this
principle."

"The suddenness of the compression or expansion," said Mr. Wilton, "is a
matter of no consequence. The effect is the same whether the operation be
sudden or slow, but if the compression or expansion be slow, the heat or
cold generated is less apparent; the heat is dissipated as fast as
produced and the colder gas is warmed by the vessel which contains it.
Ansel, how shall we explain this?"

"I cannot explain it, sir."

"The explanation is very simple," said Mr. Wilton. "Mechanical force is
employed in the compression of the gas; the force is expended and used up
upon the gas, and appears again in the form of atomic heat motion. In the
expansion of gases the operation is just the reverse; the atomic heat
motion is expended in producing expansion, and hence disappears as heat.
The general principle is that no force can be expended in two ways at the
same time.

"One other point we must notice to-day, that is, _specific heat_. What is
understood, Ansel, by this term, specific heat?"

"The relative amount of heat which different substances require to raise
their temperature through any given number of degrees."

"That is right. I think that you all must have noticed that it requires
much more heat to raise the temperature of some bodies than others. What
an amount of heat is required to raise the temperature of water! That heat
which will raise one pound of water one degree will cause an equal
increase of temperature in five pounds of sulphur, or four pounds of air,
or nine pounds of iron, or eleven pounds of copper, or thirty pounds of
mercury, lead, or gold. This is what is meant by saying that one substance
has a greater capacity for heat than another. The specific heat of water
is greater than that of any other known substance except hydrogen gas.
This fact, taken in connection with its great specific latent heat and its
poor conducting qualities, renders it exceedingly important in regulating
climate and moderating extremes of temperature; of this you will be
reminded very often as our lessons go on.

"No law or principle determining the specific heat of the various elements
and explaining the different capacities for heat has as yet been
discovered. It has been suggested that specific heat depends upon the
number of atoms, that it holds an inverse ratio to their combining
numbers, or, what is the same thing, a direct ratio to the number of
atoms. This would harmonize well with the dynamic theory of heat, but the
harmony between the specific heat of substances and the number of atoms is
not sufficiently uniform to establish this supposition.

"This completes our review of first principles. I hope that this not very
entertaining review of your academic studies has not wearied you of the
very word _heat_ and worn out your interest in examining God's management
of heat before making a beginning."

"I think," said Samuel, "that we are not in the habit of becoming
disgusted with our studies."

"You may expect," continued Mr. Wilton, "if the past has been interesting
to you, that the lessons to come will prove more interesting still. Next
week we shall consider the abundant provision which the Creator has made
for warming the earth."

And let me say to you, patient reader, that if I had known that you were
as familiar with the laws and principles of heat as Ansel, Peter, and
Samuel seem to have been, this and the preceeding chapter would not have
been written. However dull this review may have seemed to you, it was
needful, perhaps, for others, that they might understand the wonderful
works of God which we shall now proceed to examine. And, reader, do not
forget that heat itself, that subtle motion and mighty force, with all its
laws and principles, is one of God's works. Already have we been looking
at the Creator's handiwork. Already have we been trying to trace out the
thoughts of God as they are written in the "Bible of Nature." The thoughts
of God are great and wonderful. It has been useful and interesting to read
thus far in this book written with the finger of the Creator of worlds and
of man, even if we turn not another page.



CHAPTER VI.

MANAGEMENT AND SOURCES OF HEAT.


While the lessons which have been reported were going on, the religious
interest in the church was deepening. Mr. Wilton did not cease to make his
sermons instructive, but, in addition to the instruction, he made them
more and more pungent and persuasive. He aimed to gather up the
impressions and convictions already wrought in the minds of his hearers
and combine them for united and immediate effect. He believed that this
was to be a reaping-time.

Mr. Hume was becoming interested, not because he had been at church, for
he had not been there, but the Holy Spirit of God was working upon his
heart. He was becoming uneasy in his unbelief. For some reason, he knew
not why, his opinions were becoming more and more unsettled. He did not
like to go to the house of God; his self-will and pride of consistency
rebelled against the thought of hearing and believing the gospel; but he
was restless and discontented away from the place of worship. His
associations with his infidel comrades grew distasteful. His Sundays were
days of distress: with his attention relieved from business cares,
thoughts of God and eternity pressed upon him, and he could not escape
them. At length he determined to go and hear Mr. Wilton again: perhaps he
should hear something which he could so positively reject as to set his
mind at rest. He went, accordingly, the next Lord's Day, and heard a very
impressive sermon.

The text for the forenoon was Ps. lxvi. 5: "Come and see the works of God:
he is terrible in his doing toward the children of men." The sermon gave
first a brief and rapid review of some striking displays of God's
displeasure at the sins of men: that ancient world of men whose "thoughts
were only evil continually" he overwhelmed with the flood; he burned with
fire from heaven Sodom and Gomorrah, Zeboim and Admah, those lascivious
and festering cities of the plain; he sent his torturing and consuming
plagues upon the Egyptians, and sunk the army of Pharoah like a stone in
the deep waters of the Red Sea: "they sank as lead in the mighty waters;"
he caused the earth to open and receive Korah and his adherents, and bade
his angel in "one night" to touch with death the thousands of
Sennacherib's army. This record of divine wrath against evil-doers has
startled the consciences of wicked men, and will continue to startle them
so long as the ungodly live upon the earth. It is easy for unbelievers to
call the word of God a record of fabulous wonders, but that record lives
and will live, and its words assert their divinity by touching and burning
the consciences of men as if they were tongues of fire.

"But to the thoughtful man," said Mr. Wilton, "there is a manifestation of
God's displeasure at sin even more impressive than these miraculous
judgments. The Creator has built his wrath against sin into the very
fabric of the universe; he has written it upon the very atoms and elements
of matter and of mind, and graved it upon the 'nature of things.' The
forces of Nature are all instinct with holy wrath against ungodliness.
Evil doing works out evil consequences by the regular course of nature.
Babylon, Nineveh, and Tyre were great and prosperous, and as mighty in
wickedness as in commerce and war. In the height of their prosperity God
denounced upon them disaster and desolation, and by the natural processes
of evil their decay and destruction came upon them. No miracle broke the
harmony of their mighty march to decay and the silence of death. Great
nations have perished, but not till they became corrupt. Rome fell, but
luxury first gendered luxuriant vices, and vices enervated her hardihood
and undermined the defences of her courage. No righteous nation ever
perished. No nation ever fell into decay till ripe in sin and ready for
moral putrefaction. But against wicked and corrupt nations wars and
desolations are determined, and the end thereof is with a flood. The very
forces of Nature seem allied in firm compact with the laws of God, ready
with resistless hand to avenge their transgression and to visit evil upon
evil-doers. This steady march of all the forces of the world in bringing
decay and wretchedness upon sinners is more impressive than any single
desultory example of avenging wrath.

"But perhaps an unbeliever replies, 'Not so; there is a natural law of
development, decay, and death, apart from sin. Trees grow up, become old,
and die. Men pass from childhood up to manhood, and from manhood down to
second childhood, and return to the dust whence they came. By a like
principle, nations pass through similar changes of development, decay, and
desolation. But in all this there is no manifestation of divine favor or
disfavor.'

"This is narrow and false reasoning. If a single great city had become
corrupt while all the world beside remained righteous, and God had
denounced his displeasure upon it and had executed his wrath by sudden and
tremendous judgment, that one city standing out in single and solitary
ungodliness and desolation, who would deny, who could deny, that the fate
of that unhappy city was a manifestation of divine displeasure? If a
second example were made of a second ungodly city, would the expression of
divine wrath be weakened? Nay; every man would say that it is made
stronger. What if a third example be made of a third city? What if every
wicked city is made an example? What if God embody his displeasure at
evil-doing in the structure of the world, and give to the very atoms of
matter and the elements of mind such natures that by the working of their
own proper forces, without a miracle, they shall bring pain and evil,
decay and death, upon the ungodly? What is this but writing his wrath
against sin upon the earth and sky, upon matter and the consciences of
men, declaring by this that till the heavens and the earth and the spirits
of men be no more he will never withdraw his indignation? This is what God
has done. The wicked man sets in motion the machinery which works out his
own everlasting undoing. His own hand sows the seeds of death, and as
those seeds germinate they strike their roots into his corruptions and
draw their nourishment from his evil life. Thus do sinners go on
'treasuring up wrath against the day of wrath and revelation of the
righteous judgments of God.'

"But remember that God has not left the world in these later ages without
the testimony of wrathful judgments which ought to startle and alarm the
consciences of the wicked like the fires of Sodom. Let me give you what I
suppose to be a true record of the fate which befell a band of bold
blasphemers. In that uprising of infidelity which took place near the
close of the last century there was formed at Newburg, N. Y., through the
influence of a man known as 'Blind Palmer,' an association of infidels
under the name of the Druidical Society. The object of the society was to
uproot and destroy revealed religion. In pursuit of this object they
descended to the most blasphemous mockery. At one of their meetings they
burned the Bible, baptized a cat, partook of the bread and wine as
appointed for the ordinance of the Lord's Supper, and gave the elements to
a dog. Then the wrath of God broke out upon them. 'On the evening of that
very day he who had administered the mock sacrament was attacked with a
violent inflammatory disease; his inflamed eyeballs were protruded from
their sockets; his tongue was swollen, and he died before morning in great
bodily and mental agony. Dr. H----, another of the same party, was found
dead in his bed the next morning. D---- D----, a printer who was present,
three days after fell in a fit, and died immediately. In a few days three
others were drowned. Within five years from the time the Druidical
Society was organized all the thirty-six original members--actors in the
blasphemous ceremonies spoken of--died in some strange or unnatural
manner. Two were starved to death, seven were drowned, eight were shot,
five committed suicide, seven died on the gallows, one was frozen to
death, and three died, the record says, _accidentally_.' Be sure of this:
God has not left the world nor forgotten his judgments against his
enemies, neither is he tied up and hampered by the laws of Nature. 'God is
angry with the wicked every day. If he turn not, he will whet his sword:
he hath bent his bow and made it ready. He hath also prepared for him the
instruments of death.'

"But remember, also, that God does not limit his expression of wrath to
these natural agencies. The smile of God beams direct upon the soul as the
warm rays of the sun fall upon the cold earth, and the frown of God throws
a shadow which darkens the soul with the gloom of eternal death."

This discourse stirred the mind of Mr. Hume in a wonderful manner. The
story of God's judgments upon wicked men and dissolute cities he had read
many a time in his boyhood, but the rapid review of them by Mr. Wilton
seemed to bring them up with a lifelike vividness. And that view of the
forces of Nature, as allied with the moral laws of God to work out wrath
upon evil-doers, was new to him, but his own mind quick as thought
suggested many more illustrations than Mr. Wilton had time to give. He
remembered that all manner of vices--drunkenness, lust, devotion to gay,
sensual pleasures--bring ruin to men. He had noticed that the saddest
faces are those of worn-out lovers of pleasure, and he knew that lovers of
pleasure are very quickly worn out--that five years of sensuality will
waste the powers of life more than fifty years of good work. He knew also
that infidels and blasphemers, whatever else they might be, were unhappy
men, and died joyless, foreboding deaths. He was not exactly angry, but
his heart rebelled against thus being held by the mighty power of God,
willing or unwilling, and against the thought that even Nature herself had
conspired against him. It seemed to him hard that he was born into such a
world, and that there was no escape from it. He did not consider at the
moment that God and his works were against him only because he was
against God, and that by submitting to God in loving obedience all the
forces of God's world and God's providential government would turn in his
favor--"that all things work together for good to them that love God."

At length better thoughts came to him. "I must know," he said to himself,
"whether these things are so. I have never examined the subject to
discover the truth, but have tried to find reasons for disbelieving the
Bible and denying the gospel. I ought to look at the other side. If Nature
and Nature's God have blessings in store for the willing and the obedient,
why should not I know this and receive my share?"

Under the impulse of thoughts like these he formed the sudden resolution
to join Mr. Wilton's Bible class--that is, if he would receive him
willingly, of which he had no small doubt. Coming directly forward at the
proper time, he said to Mr. Wilton:

"I have learned what your class is studying, and should like, I hardly
know why, to join your class for a few Sundays, if you are entirely
willing."

Mr. Wilton, of course, did not know the exact state of Mr. Hume's mind;
he did not know but that he came with a contentious spirit to bring up
objections and propose hard questions; but he felt certain that, whatever
his state of mind, the Spirit of God was bringing him to take this step.
He had prayed for him; in prayer his soul had travailed in pain for him;
and he felt that by way of the throne of grace he had obtained a hold upon
Mr. Hume--that the Holy Spirit had bound a cord between them which could
not be broken. He believed, therefore, that, whether he came penitent or
angry, good would result from his coming. He gave him, therefore, a hearty
welcome.

"I am not only willing," he said, "but very glad, to have you come; and as
I know that you have kept yourself informed of the latest phases of modern
science, I hope we shall have your help in unfolding the subject which we
are engaged in studying. I think you will be able to do us good."

"Your kind welcome ought certainly to incline me to do anything which I
can to help the interest of your study, but I only ask the privilege of
sitting with your class as a silent listener."

The Sunday-school opened as usual, and the classes entered upon their
work.

"You have come in, Mr. Hume, at just the proper point in the progress of
our lessons," said Mr. Wilton. "We have been preparing the way by a brief
review of the laws of heat. We have gone over the effects of heat; the
conduction, radiation, and convection of heat; thermal reflection,
absorption, and transmission; specific and latent heat. We have tried to
form a conception of the existence and operations of heat according to the
dynamic theory that heat is a mode of atomic motion. This review would
have had little interest to you. We are now prepared to look at the
goodness and wisdom of God in the management of heat. We are not trying to
prove the existence of a Creator and Governor--we are only looking at the
mighty and wise works of that God in whom we already believe. We shall
find the works of God planned and wrought out with wondrous skill, and
that wonderful skill is employed in the interest of goodness. God has
planned and wrought for the benefit of his creatures. His wisdom and
goodness are exhibited on the grandest scale and in gigantic proportions.
This is all that is needed practically to demonstrate the existence of
God. A good conscience does the rest. Being once assured that there is a
Creator, a good conscience leaps to the conclusion that we ought to obey
and serve him. Nay, the very work and existence of a conscience implies a
divine Lawgiver and Ruler. To a good conscience a God is a necessity. But
as we are not now attempting to show that there is a God, but to study his
works, we will pass this point.

"With respect to the subject before us, let us first notice that heat is a
necessity to the world and to man, and that God has made ample provision
for that need. What the condition of the world would be without heat we
can only conjecture. In the polar regions a natural temperature of seventy
degrees below zero has been observed. At this temperature all the water
upon the globe would turn to ice hard as adamant; all vegetation would
cease, and with the disappearance of vegetable life all animal life must
perish. The whole earth would be a frozen, lifeless, silent waste in the
midst of silent space. Some lines in Byron's picture of universal darkness
would fitly describe the state of the world:

    'The waves are dead, the tides are in their grave,
    The winds are withered in the stagnant air,
    And the clouds are perished.'

This description would be no figure, for motion as well as life depends
upon heat. Yet seventy degrees below zero is but the beginning of cold.
'By mixing liquid protoxide of nitrogen with bisulphate of carbon in a
vacuum, M. Natterer produced a temperature of two hundred and twenty
degrees below zero.' At this temperature some of the so-called permanent
gases--as carbonic acid, chlorine, and ammonia--can be compressed into
liquids, and it is believed that in the complete absence of all heat all
the gases would become solids. But by the agency of heat the world teems
with active life. Vegetation clothes the earth with a garment of beauty;
and earth, air, and sea swarm with living creatures full of enjoyment.
This great need of the world is bountifully supplied. The power and wisdom
of God are employed in producing happiness.

"This, however, is but a part of the benefit which heat confers upon the
world. The chief inhabitant of the earth is man, and man was created for
something higher than bare existence. He was created for civilization and
culture. The savage state is not, as some self-styled philosophers dream,
the natural state of man. Nothing is so much against Nature. The natural
state is that condition in which he attains the fullest development. Let a
brute be placed in so unfavorable conditions that his growth is dwarfed
and his natural instincts are not called into exercise, and no one would
look upon that as a natural state. But man, wild, uncultured, undeveloped,
is spoken of as being in his natural state. There could be no greater
mistake. Culture and civilization are according to Nature, but culture and
civilization require that man should get the mastery of Nature and subdue
her forces. Till man gets the victory over the forces of this rough world,
he spends a precarious existence in a hard struggle to gain a meagre
support for his animal life. But when once science brings art, and the
mastery of Nature is gained, man can rise into culture and beauty.
Opportunity is given for development. He blossoms into greatness and
strength. Ideal and spiritual ends take the place of mere subsistence.

"But by what agency does man achieve the mastery of Nature? By the agency
of heat. By the aid of heat man subdues the world. Heat brings the
lustrous metal from its native ore; heat fashions the metal into a
thousand shapes for the use of men; heat reigns as king in the curious
processes of the chemist's laboratory, and the laboratory is the mother of
all those modern arts which bless and beautify human life. By heat man
prepares his food; by heat he drives his machinery; by heat he outstrips
the flight of the winds; by heat he turns winter into summer and in his
own dwelling makes for himself a perpetual springtime. For these purposes
of human comfort and culture, God has provided generous stores of heat and
placed them under man's control. He has placed in man's hands the means by
which he can generate a heat which devours the hardest metals like stubble
and a cold greater by far than Nature ever produces. We see that the
Creator has provided for man as a being susceptible of culture and
development, as a being of soul and sentiment, of spirit and aspiration.
God has fitted the world to be the dwelling-place of spiritual beings like
man."

"I beg your pardon," said Mr. Hume at this point, "that the first word I
speak in your class should be a question which amounts to an objection."

"I shall be glad," said Mr. Wilton, "to hear your question, even though it
be an objection. I will also answer it if I can."

"I wished to ask why it is, if God designed to provide for man's wants,
that man can supply his wants, especially his higher wants--the wants of
his intellectual and spiritual nature--only with the greatest difficulty
and toil? The brutes supply their need with comparative ease, but man with
boundless thought and labor."

"Your question is an important one, and deserves an answer. For myself, I
look upon the fact to which you refer as one of the many points in which
this world is adapted to human needs. Man is put in a condition which
requires boundless thought and toil for the supply of his higher wants
just because he possesses a nobler nature and such thought and exertion
are needed for its development. Which is the more desirable condition for
a young man to be placed in--one in which his every wish is anticipated
and his every aspiration is gratified without exertion on his own part, or
one in which opportunity and means are furnished for self-help, one in
which he can supply his wants and satisfy his aspirations only by the
exercise of his best abilities? Which will encourage the larger manliness
and nurture the higher culture and strength? He who has no need for
exertion rises at best only to a soft and feeble luxury, without mental
vigor or moral force. What does man need besides scope and reward for
exertion? Effort and struggle are necessities of our nature. This is
especially true of man's higher faculties. Human greatness and goodness
are not created by a word: they must be developed by exertion. For this
reason God has made exertion necessary, and as much more necessary with
man than with the brutes as his culture is more the result of voluntary,
intelligent exertion. Does this explanation seem to you satisfactory, Mr.
Hume?"

"I have no fault to find with it; I must think of it."

"Very well, then; if no other one has a question to ask, we will look at
another subject. We will survey the storehouses of heat which God has
prepared for warming the earth. Samuel, you may name the first great
source of heat."

"I think, sir, that the sun is the chief source of heat."

"We certainly receive the larger part of our heat from the sun. No one can
doubt this. So much of our heat comes from the sun that the temperature of
the earth varies according to the sun's heat, as if that were the only
supply. If but a fleecy cloud pass between the sun and the earth, we feel
a decided change of temperature. A few hours less of sunshine each day,
and a few degrees more of inclination to the sun's rays, change summer to
winter and make the difference between the torrid and the frigid zones.
Withdraw the heat of the sun altogether, and the whole world would become
a desert of frozen death."

"What is the cause of the sun's heat?" asked Peter.

"You have asked a question which I cannot answer, and which no man can
answer. The most careful and patient observations have been made to
discover if possible the constitution of the sun; learned and curious
conjectures have been brought forward to explain the source of its heat;
but the positive results have not been very large. It is certain that the
sun is a globe revolving upon its axis in a period of twenty-five days,
nine hours, and thirty-six minutes. This is known by the motion of dark
spots upon its surface. The appearance of the sun as seen through a
telescope is that of a globe of fire, its surface often in a state of
violent agitation and flecked here and there with dark, irregular,
changeable spots. These spots are sometimes of enormous dimensions--thirty
thousand or fifty thousand miles in diameter. They present a dark centre
with a narrow border or penumbra of lighter shade. To account for these
spots, it has been conjectured that the body of the sun is dark, but
surrounded by a double envelope of clouds, the outer layer of which is
intensely luminous. Openings in such enveloping clouds would present an
appearance like the spots upon the sun. According to this supposition, the
heat and light of the sun proceed, not from the body of the sun, but from
this luminous enveloping cloud. But granting that this supposition is
true, it gives no explanation of the origin of the sun's heat. Laplace
conjectured that the sun is a globe of fire in a state of violent,
explosive conflagration, and that the spots are enormous crater-like
caverns in its surface. Newton conjectured that comets falling into the
sun and being consumed feed the solar fires and maintain its temperature.
The reception of the dynamic theory of heat has led to the revival, in a
modified form, of this conjecture of Newton. It is suggested that meteors
or meteoric matter falling into the sun generates its heat by the force of
concussion. To show that the intense heat of the sun might be thus
generated, elaborate calculations have been made. It has been demonstrated
that if the sun were a solid mass of anthracite coal, its combustion would
maintain its heat at its present rate of emission only five thousand
years, while the falling of the planet Jupiter into the sun would generate
an equal amount of heat for thirty-five thousand years. A lump of coal
falling from the earth to the sun would produce three thousand times more
heat by the concussion than by its combustion.

"The nearest approach that has been made, of an exact and scientific kind,
toward determining the constitution of the sun's surface has resulted from
an examination of the _solar spectrum_. A ray of light, by passing through
a triangular prism of glass, is, as you know, divided into its elements,
or constituent colors. The ray of light is spread out like a half-open
fan. This divided and expanded ray, thrown upon a screen, is called the
spectrum. An examination of the solar spectrum by a microscope shows
certain fine dark lines across it. The lines are invariably the same in
their position and grouping. The spectrum of the stellar light is found to
differ from that of the solar light, and the light of one star differs
from that of another star. Light from incandescent metallic vapors gives
bright lines across the spectrum. Each metal has its own number, position,
grouping, and color of these spectral lines. By comparing the solar
spectrum with the spectra of the various metals--the processes are curious
and the explanation difficult to be understood--corresponding lines are
discovered, and the conclusion is reached that the sun's atmosphere
contains the vapors of several of our well-known metals, as iron, nickel,
sodium, potassium, and others. This is a most curious and marvelous
scientific feat, to make an approximate chemical analysis of the sun and
stars by means of their light. The conclusions, however, seem
trustworthy.

"Can you tell us, Ansel, whether the earth receives heat from the moon and
stars?"

"I cannot, sir."

"I should be glad, Mr. Hume, to have you instruct us upon this point."

"In regard to the fixed stars," answered Mr. Hume, "counting them as the
remote suns of other planetary systems, we must believe that they radiate
more or less heat upon the earth; some indeed have extravagantly
maintained that we receive from them nearly as much heat as from the sun.
The heat received from them is so small that we perceive no difference
whether they be hidden, or shine with their utmost brilliancy. I do not
know that investigations have been made to determine scientifically their
exact thermal influence upon the earth. But little more can be said about
the heat of the moon. The light of the full moon, concentrated by a
two-foot burning-glass and thrown upon the bulb of the most delicate
thermometer, produces no perceptible effect. By means of the electroscope
or galvanometer, it is said, however, that the moon's heat has been
detected. At a late scientific convention held in Chicago, Prof. Elias
Loomis read a paper, in which he stated that Mr. Harrison of England, by
a comparison of observations made for sixteen years at Greenwich, nine
years at Oxford, and sixteen years at Berlin, has discovered that the moon
exerts a sensible influence upon the temperature of the earth, the highest
temperature occurring from six to nine days after the new moon and the
lowest about four days after the full moon. The conclusion, the opposite
of what we should naturally expect--the higher temperature occurring when
the enlightened face of the moon is turned from the earth--was explained
by supposing the moon's heat to be dark heat which would be absorbed by
the vapors and the clouds, and thus tend to warm and dissipate them. By
the dispersion of the clouds, the radiation of heat from the earth's
surface would go on more rapidly and the temperature would fall. According
to this explanation, the lunar heat reduces instead of raising the
temperature of the earth. The difference of temperature due to the moon's
influence Mr. Harrison believed to be two and a half degrees. Upon
extending his calculations through forty-three years of observations made
at Greenwich, he found the difference reduced to about one degree. As for
myself, I confess myself still a skeptic touching the supposed influence
of the moon upon temperature."

"Upon that subject, I think," said Mr. Wilton, "that we must wait
patiently for more light. The popular superstitions which refer sickness
and health, and every kind of good or evil fortune, to the benign or
malignant influence of the moon, we, of course, must reject. Samuel, will
you name the second chief source of heat?"

"I am obliged to answer as Ansel answered just now--I cannot tell. The
enormous amount of wood and coal burned amounts to something, but this can
have very little effect upon the temperature of the earth."

"The second great store of heat is the internal heat of the earth," said
Mr. Wilton. "The importance of this store of heat we can easily understand
by considering that the earth is a mass of molten mineral matter cooled
and hardened upon the surface. The crust upon which we live is warmed from
beneath by an ocean, or rather a globe, a world, of glowing molten rock.
Deep excavations have been made in mining operations, and artesian wells
have been bored to still greater depths--as deep as two thousand, three
thousand, or thirty-five hundred feet. The heat of the sun penetrates not
more than seventy-five or a hundred feet; below that depth the temperature
of the earth remains the same throughout the year. Below the point of
constant temperature the heat of the earth is found to increase regularly
and constantly. The rate of increase varies in different regions, but the
average rate is about one degree of temperature for each fifty or sixty
feet of descent. From this rate of increase it is easy to calculate the
temperature at any given depth. At a depth of less than two miles water
would boil. At twelve miles in depth the rock becomes incandescent. At
twenty-two miles silver melts, at twenty-four miles gold melts, and at
thirty-five miles cast iron becomes liquid. Volcanic eruptions also
demonstrate the existence of immense masses of molten rock in the interior
of the earth; and we can account for the existence of volcanoes only by
supposing that they now communicate or once communicated with the deep
interior heat of the earth. The thickness of the earth's crust is,
however, a matter of conjecture. The melting point of different substances
rises as the pressure upon them increases, and as the density of the rock
increases its conducting power becomes greater. The crust of the earth,
therefore, may be fifty miles in thickness, or it may be one hundred miles
or two hundred or three hundred miles. The effect of this internal heat in
maintaining the temperature of the earth must be very great."

"I want to ask," said Peter, "how this internal heat came to exist, and
how it is maintained?"

"This, like your former question, is altogether beyond our knowledge. All
that we certainly know is that God made it thus. The process of creation,
if indeed God did not create the earth by a word, without a process, is a
matter of sublimest and most venturesome conjecture. According to the
opinion of some, the elements of which the earth is composed were created
separate and uncombined, and were suffered afterward to unite by their
chemical affinities. This chemical combination would be nothing else than
a tremendous conflagration, and the result would be the most intense heat
of which we can form a conception. Others have dreamed of a 'fire-mist'
created of God and by some means condensed into worlds. The temperature of
the earth is maintained, so far as we know, only by the poor conducting
quality of the enveloping crust preventing its cooling. At the present
rate of radiation, millions of years would be required to render the
change of temperature perceptible.

"What is the third great natural source of heat? I will ask Mr. Hume."

"Mechanical action, or force transmuted to heat."

"Will you please explain this?"

"Strictly speaking," said Mr. Hume, "this is not to be counted an original
source of heat. But heat is used in the production of winds and waves, the
flow of rivers, and all the ceaseless activities of the world, and this
force reappears from time to time transmuted again to heat. Whenever in
the friction of air and of water, in the dashing of matter against matter
and force against force, motion and force seem to be lost, heat is
produced. The water of the sea after long storms is said to be sensibly
warmed. We can appreciate the amount of heat generated in this manner only
by considering in how many thousand ways force is meeting force and motion
is destroyed. All this lost motion--lost as sensible motion--reappears as
atomic motion, that is, as heat. Such heat has been applied to artificial
uses. Heat generated by the friction of iron plates ground together has
been used for heating buildings."

"And this transmutation of living force and heat," added Mr. Wilton, "is
but one of many illustrations of God's economy in the management of heat.
Nothing is wasted. The voices of Nature all echo the words of Jesus:
'Gather up the fragments, that nothing be lost.'

"The fourth source of heat is chemical action. What is the chief form of
this which is used for the production of heat? Samuel may tell us."

"Combustion, I think, sir."

"That is right; and the most common form of combustion is the combination
of carbon with oxygen. This is commonly employed, not because it generates
the most intense heat, but because carbon exists so abundantly, and is the
most available and the cheapest. The most common form of carbon is wood
and coal. This is that storehouse of heat which God has placed in man's
keeping. Without this the larger part of the earth's surface would be
uninhabitable. This renders culture and civilization possible. Without it
the arts could have no existence. The key of this storehouse of heat God
has given to man, so that he may enter in and use its treasures at his
pleasure. In the finer arts where very great heat is required, hydrogen is
used in place of carbon. Jets of oxygen and hydrogen gas thrown together
constitute what is called the oxy-hydrogen blowpipe, and generate the
intensest heat which can be produced by man.

"Another source of heat not often mentioned is electrical force. This,
like mechanical force, may be transmuted into heat. An electric current
sent through an insufficient or poor conductor heats it, and, if the
current be sufficiently strong, consumes it. Thus lightning-rods are
sometimes melted and buildings set on fire.

"These, then, are the natural reservoirs of heat: 1, the sun and other
heavenly bodies; 2, the internal heat of the earth; 3, living force, or
motion; 4, chemical action; 5, electric force.

"We can hardly over-estimate the abundance of these natural supplies of
heat. The world is warmed on the most munificent scale. The earth receives
from the sun heat sufficient to boil three hundred cubic miles of ice
water per hour, and the whole sum of the sun's heat would boil
700,000,000,000 cubic miles of ice water in the same time, that is, the
heat radiated by the sun would boil a mass of ice water of the size of our
globe in twenty-five minutes.

"The amount of carbon provided by the Creator is enormous beyond
conception. Vast regions of country are covered with dense forests, but
the fuel from the forests is but a handful in comparison with the fuel
stored up in coal-beds below the surface of the earth. Mr. Mitchel
estimated the extent of the coal-beds of a portion of Europe as follows:
Great Britain, 12,000 square miles; Spain, 3500; France, 1700; Belgium,
5180. Mr. R. C. Taylor has made a like estimate for North America, giving
to British America 18,000 and to the United States 134,000 square miles.

"These estimates, you will notice, say nothing of Asia, Africa, South
America, or the islands of the sea, and include only the smaller part of
Europe. In the United States, also, new coal-fields are constantly
discovered. The supply of carbon for fuel seems exhaustless. In the
British islands about 100,000,000 tons of coal are mined annually. At this
rate the known supply would last for a thousand years. In the United
States the supply has no known limit.

"You will keep in mind that this supply of heat is also a supply of
mechanical force. The coal-fields are an exhaustless storehouse of heat
and power. They warm the dwellings of man and drive millions of engines
working with the strength of Titans for human welfare.

"In this bountiful supply of heat to warm the earth and serve human needs
must we not see a kind design on the part of the Creator? God has provided
that which the world needs. He has provided without stint or limit. The
general heating of the globe he accomplishes by his own power. He has
provided for human culture, development, and happiness by placing stores
of heat under man's control. He has furnished scope and means and
encouragement for achieving greatness and goodness. He has put man in the
condition which a wise father would desire for his son.

"In our next lesson we will look at the preservation and distribution of
heat, some of the primary elements and arrangements upon which the
temperature of the earth depends."



CHAPTER VII.

PRESERVATION AND DISTRIBUTION OF HEAT.


Another Lord's Day comes, and the members of the class are, as usual, all
in their places. They find the subject increasing in interest after
leaving the review of the laws and principles of heat.

"A week ago," said Mr. Wilton, "we looked at the chief sources of heat.
These are the sun, the internal heat of the earth, chemical action, in
which combustion is most important, electrical action, and mechanical
action, or 'living force.' The amount of heat furnished from these sources
is above all comprehension. The Creator seems bountiful even to
prodigality in supplying heat for the needs of the world and the uses of
man. But with all this largeness of supply the provision would prove
wholly inadequate if it were not prudently husbanded and all the avenues
of waste carefully closed. Men of ample incomes sometimes come to want
from too free expenditure. Their incomes are large, but their expenses are
larger. So it would prove in respect to heat if Nature were not as prudent
in saving as she is bountiful in providing. Will some one mention some of
the general methods by which the waste of heat is prevented?"

No one answered. Mr. Hume did not think it best to put himself forward in
answering questions, and therefore answered only when personally
addressed. The others were silent because they had nothing to say.

"I see that I shall have to suggest the answer. Ansel, what part of the
atmosphere is warmest?"

"The bottom, I suppose, for the higher a man goes up upon the lofty
mountains or in a balloon, the colder he finds the air."

"That is right; and we need to ascend only about three miles, even in the
tropics, to reach the region of perpetual snow, while in the polar regions
the line of perpetual freezing comes down to the sea level. What would be
the effect, Ansel, if the atmosphere were as warm, or warmer, at the top
than at the surface of the earth? How would that affect the rate of
radiation from the earth?"

"It must, of course, increase the radiation very much. With the
temperature twenty or fifty or seventy degrees below zero, the radiation
must be very little."

"By some means, then, the atmosphere is kept warm at the surface of the
earth and cold in the higher regions, and in this manner the radiation of
heat into open space is prevented. This is accomplished notwithstanding
that the top of the atmosphere is nearer the chief source of heat, the
sun. This would be no very easy problem if its solution were left to human
ingenuity. The explanation is very simple, however, when once suggested.
The atmosphere is diathermic, that is, it permits the luminous heat from
the sun to pass directly through it without heating the air, but the solid
earth stops the heat by absorption, and is warmed by it. The warm surface
of the earth imparts, in turn, its heat to the atmosphere resting upon it.
This warm air, being expanded by the heat received, becomes lighter than
the cold air around, and rises, or rather is forced, upward by the
greater weight of the colder air. But as it rises and the pressure of the
air is diminished it expands still further. By this expansion its sensible
heat becomes latent, that is, the heat is transmuted into force, and, as
force, is incapable of being radiated. In this manner radiation from the
upper surface of the atmosphere is greatly hindered and waste of heat is
in a good degree prevented.

"In respect to this heating of the atmosphere from the surface of the
earth, a layer of clouds sometimes forms a kind of second surface which
receives the sun's rays and warms the air above. A few years ago I saw a
balloon ascension in Providence, R. I. The day was bleak and chilly, and
the sky entirely covered with clouds. The aeronauts were expecting a
chilly voyage. The balloon shot like an arrow toward the zenith, and in
five minutes was completely hidden by the clouds. But to the surprise of
the voyagers of the sky, on passing through the clouds their thermometer
rose ten degrees. This, doubtless, must very often be the case. The air
above the clouds must often be warmer than that below.

"I think you all must have noticed illustrations of this principle on a
small scale. Have you not seen that snow and ice often melt around straws
and sticks, the snow or ice remaining still frozen at a little distance,
as if the sticks and straws were warm and had melted them? Have you not
seen a dark-colored board covered with ice, and the ice remain firm till
the sun shone upon it, and then the ice melt upon the under surface,
leaving the upper surface unaffected?"

"I have seen such things a great many times," said Peter, "and wondered
what the reason was."

"The reason is that ice is _diathermic_. Heat passes through the ice
without warming; but when the rays of heat fall upon the stick or stone or
board, the heat is absorbed, the dark body is heated and in turn warms and
melts the ice. In the same manner the atmosphere is warmed. The heat-rays
of the sun pass through the atmosphere and fall upon the surface of the
earth; the earth is warmed, and in turn warms the air resting upon it.

"The gases and watery vapor contained in the air also hinder the radiation
of heat from the earth. Pure atmospheric air is perfectly diathermic to
both luminous and dark heat, and vapors and gases are also diathermic to
luminous heat. But to dark heat some of the gases are almost impenetrable.
Ammonia stops dark heat almost completely. In a smaller degree watery
vapor does the same. Gases and vapors thus serve as blankets to keep the
earth warm. The heat of the sun, being luminous heat, penetrates the
atmosphere with its vapors and foreign gases, and falls upon the earth
almost without loss, but, being absorbed by the earth, it becomes dark
heat, and cannot be radiated back through the same gases and vapors. Vapor
serves thus as a valve: it admits the heat of the sun to the surface of
the earth, but prevents its escape. Prof. Youmans calls watery vapor the
barb of heat; it catches the heat of the sun and holds it fast.

"Who can sufficiently admire the simplicity of these arrangements for
preventing the radiation of heat into the stellar regions?--and their
efficiency is no less admirable than their simplicity. Arrangements like
these show that the Creator had a definite object in view, and that object
is benevolent. For the advantage and enjoyment of the inhabitants of this
world these arrangements were made.

"We ought at this point to look at those adjustments by which the earth
receives just the amount of heat needed to maintain the requisite
temperature. The importance of maintaining some certain average
temperature cannot be over-estimated. Every animal and plant has its own
_habitat_--that is, its natural dwelling-place or location--outside of
which it perishes or maintains a stunted and precarious life. The habitat
of animals and plants depends in a very great degree upon temperature.
What a panorama would be seen if we could fly like a bird from the equator
to the poles, and look down upon the ever-changing animal and vegetable
life as we pass! How the luxuriant vegetation and flaunting colors of the
tropics would shade off into the scantier vegetable life and more sober
hues of the temperate zones, and these in turn die out and disappear in
polar barrenness! We should see the lion and tiger give place to the bear
and the wolf, the elephant and camel to the ox and horse, and these to the
white bear and reindeer. This sublime panorama we see, in miniature, in
ascending lofty mountains in the tropics. Around the base of the mountain
flourish the rich and various productions of the torrid zone; a few
thousand feet of elevation bring us among the productions of the temperate
zones. The most valuable fruits and grains thrive. Then vegetation becomes
scanty and stunted, and at last disappears. The top of Mt. Washington,
6234 feet high, in latitude forty-four degrees, is as bare of trees and
plants and every form of vegetation as the north pole.

"The fitting temperature is almost as necessary to the animal tribes as to
vegetable life. Animals which are native to the tropics do not thrive in
colder countries, or if the difference of temperature be very great, they
perish. A change from a cold to a warm region is equally disastrous. Man
indeed transfers animals from their natural habitat by protecting them
from the extremes of temperature, but this is, of course, no exception to
the general principle of which I am speaking. A change of only a few
degrees in the mean annual temperature would render this earth a hard
place for even the human race to subsist. But the temperature of the earth
depends upon many a wise adjustment--how many, we cannot tell. Will you
tell us, Samuel, the first adjustment or arrangement upon which the
temperature of the earth depends?"

"It must depend chiefly I think upon the intensity of the sun's heat."

"Whether or not that be the chief adjustment by which the right
temperature is secured, it is at least a very important item. The
intensity of the sun's heat must, of course, be considered in connection
with its distance from the earth. The distance of the sun is no less
important than the power of his rays; indeed, in one sense, it is more
important, for if the intensity of the sun's heat were doubled, the
temperature of the earth would be increased only twofold; whereas, if the
earth were brought to one-half its present distance from the sun, the heat
would be increased four times. Heat being one of the radiant forces, its
intensity diminishes in proportion to the square of the distance through
which it acts. If the earth were 190,000,000 of miles from the sun instead
of 95,000,000, as it now is, the force of the sun's rays would be
diminished fourfold. The Creator has so fixed the distance of the earth
and sun, and the power of the sun's heat, as to give to this world a
temperature suited to its various inhabitants.

"The temperature of the earth has also some dependence upon our
atmosphere. Can you tell us, Ansel, how the temperature of the earth is
affected by the atmosphere?"

"You have already told us that the atmosphere is _diathermic_, allowing
the heat of the sun to fall upon the earth almost undiminished in force.
If the air were so constituted as to intercept the sun's rays, it is plain
that the earth would receive less heat."

"This adaptation of our atmosphere to transmit the sun's rays," said Mr.
Wilton, "is more subtle than it appears at first sight. It is not merely a
matter of depth and density, though those are important considerations,
nor is it merely a question of the elements of which the atmosphere is
composed. Simple gases are _diathermic_. The atmosphere is therefore made
up of two simple gases, oxygen and nitrogen, not chemically combined, but
mixed together. Compound gases intercept the passage of heat. Ammonia,
composed of hydrogen and nitrogen chemically united, almost wholly stops
it. Even ozone, which is nothing but oxygen in a changed or _allotropic_
state, is not _diathermic_. The _diathermic_ quality of the air depends,
then, not only upon the fact that it is composed of simple elements
mingled, but not chemically joined, but also upon the _state_, or
_condition_, of those simple elements.

"Another point deserves attention. Oxygen is an element having a wide
range of very strong and active affinities. It is ready to unite with
every known substance, fluorine excepted. What if some other equally
active element were mingled with oxygen to form the atmosphere? What if,
in place of nitrogen, vapor of sulphur were substituted? What if hydrogen
were put in the place of nitrogen? The two elements would combine in
sudden combustion or explosion, and the atmosphere itself would perish.
But nitrogen is a substance so sluggish and inert that it can be brought
into union with oxygen only by indirect processes. Because the air is
composed of one so inert element as nitrogen, the atmosphere is preserved,
and, what is almost as important, it is kept, as it now is, composed of
simple elements, and hence _diathermic_. If our atmosphere were a compound
gas, the world would perish with cold.

"The temperature of the earth depends also upon certain qualities of the
earth's surface. I should be glad to have Mr. Hume explain this."

"I suppose," answered Mr. Hume, "that you refer to the qualities of the
earth as an absorbent and conductor of heat. The earth must needs have the
capacity of receiving and retaining the heat which falls upon it from the
sun. If the earth's surface were polished and brilliant, the heat of the
sun would be reflected into space as from the surface of a mirror, and
very small advantage would the earth receive from the solar heat. A dark
soil absorbs heat more readily than a soil of lighter color, and a wet
soil, on account of the high specific heat of water, requires more heat to
raise its temperature than a dry soil. The mineral elements of the soil
and its compactness or porosity also help to make up its capacity for
receiving and retaining heat. The color and constitution of the soil
sometimes go far toward making the climate of a region. The conducting
qualities of the earth's crust in its profoundest depths also must be
taken into account. If the crust of the earth were composed of silver, or
any other substance of like conducting quality, and the interior of the
earth were molten rock, as it now is, the interior heat would be so
rapidly conducted to the surface that everything upon the earth would be
consumed."

"Upon so many circumstances wisely adjusted and nicely blended," said Mr.
Wilton, "does the temperature of the earth depend. The intensity of the
sun's heat, the dimensions of the earth's orbit, the constitution of our
atmosphere in the subtlest qualities and relations of its elements, and
the material, structure, and color of the earth's crust,--on all these and
many other things which I cannot stop to mention depends the temperature
needful for the well-being of the inhabitants of this globe. I beg your
pardon, Mr. Hume, but allow me to ask whether such a combination of
agencies and conditions, uniting to work out good for man, does not seem
to you quite superhuman and worthy of a wise and good Creator?"

"I cannot deny it, sir," he replied; "I am not prepared to make any
objections. There are many things painful to man in the vicissitudes of
heat and cold, and if I were to make a world, I suppose I should leave
them out, or perhaps make the world upon a very different plan. But I am
not prepared to affirm that any changes which I could make would be
improvements, though I have thought until recently that more of knowledge
and power, and perhaps more of chance, too, than of wisdom and goodness,
were displayed in the works of Nature. But I must confess my opinion has
been much modified."

"I think your change of mind is in the right direction, and I am glad that
it is so. We learn the secrets of Nature and appreciate her spirit much
better when we come as reverent questioners than when we come with
preconceived notions and a patronizing air. I can well understand your
feelings and state, for I myself have traveled over the same ground. My
eyes were once dazzled with the glories of science; I worshiped at the
shrine of natural laws. But I have learned that God is greater than
Nature, the Creator is mightier than the creation. Nature has no mind or
purpose apart from the plan and will of the supreme Architect and Ruler,
and this inner plan and purpose of Nature is seen only in the government
and discipline of our sinful race. I shall greatly rejoice for you and
with you if you shall go on to the same end which I have reached."

"I shall much rejoice if I reach some satisfactory and peaceful
conclusion."

"To understand the management of heat," said Mr. Wilton, "we must take
note of the differences and fluctuations of terrestrial temperature. The
sources of heat are constant. The sun sends out its flood of heat
uninterrupted and changeless for ever. The internal fires of the earth
give an even inward heat. Mechanical and chemical agencies are active
everywhere. These sources of heat do not fluctuate, flaming up and dying
away, yet temperature is the most variable of all inconstant things. In
passing from equator to pole we go from torrid to frigid, from everlasting
summer to everlasting winter. And not only this, but in the same region
the temperature never remains the same for even twenty-four hours. The
thermometer may pass from forty degrees above to thirty below zero in a
very few hours. We must first consider the agencies by which these
inequalities are produced. Ansel may mention the first of these."

"The shape of the earth," said Ansel.

"How does the form of the earth operate to produce inequality of
temperature?"

"The earth is a sphere, and the rays of the sun fall upon it in nearly
parallel lines. Upon the centre of the hemisphere which is turned toward
the sun the rays fall perpendicularly, the sun is directly over head,
while toward the edges of the hemisphere, on account of the curvature of
the earth's surface, the rays fall more and more slanting, as if the sun
were sinking toward the horizon."

"What is that inequality of temperature which is produced by the shape of
the earth?"

"The five zones," answered Peter.

"This subject is so well understood," said Mr. Wilton, "that I need not
spend time in explaining it. Every boy knows the difference between
setting his wet slate before the fire to dry so that the heat will fall
squarely and perpendicularly upon it and placing it edgewise to the fire.
Upon the torrid zone the sun shines perpendicularly, upon the temperate
zones obliquely, and upon the frigid zones still more obliquely, and
during a part of the year the sun is entirely hidden. In proportion as the
rays of heat fall obliquely, any given amount of heat is spread, so to
speak, over a larger surface, and the larger the space over which it is
spread, the feebler it becomes. What is another cause of inequality of
temperature?" No one answered. "Samuel, what is the cause of day and
night?"

"The turning of the earth upon its axis."

"And the rotation of the earth upon its axis," continued Mr. Wilton,
"brings not only an alternation of light and darkness, but also of heat
and cold. The heat of the sun is withdrawn along with the light. The heat
of the sun is not withdrawn from the earth, but one-half of the earth's
surface is constantly turned away from its influence. This must produce a
daily change of temperature. This diurnal fluctuation of temperature may
be very small or it may amount to seventy or eighty degrees. Samuel, what
is a third cause of unequal temperature?"

"The inclined position of the earth's axis and the revolution of the earth
around the sun cause the change of seasons."

"If it were not for this, the earth would still have her zones of seasons;
a part of the earth would have endless summer, a part endless spring, and
the rest unbroken winter, but the alternation of seasons at the same place
would be unknown. The axis of the earth is now inclined about twenty-three
degrees, twenty-seven minutes, twenty-three seconds to the plane of the
earth's orbit, and as this axis maintains constantly the same position,
being parallel in one part of the earth's orbit to its position in any
other part of its orbit, during one part of the year the north pole is
turned twenty-three and a half degrees toward the sun, while in the
opposite part of the year the south pole is in like manner brought into
the light and heat. This causes the sun to appear to move to and fro,
north and south, twenty-three degrees, twenty-seven minutes, and
twenty-three seconds from the equator in either direction. The tropics, or
turning-places, mark the limits of the sun's northern and southern
journey. Everywhere between the tropics the sun, at some period of the
year, passes through the zenith, that is, exactly overhead at noon. North
and south of the tropics the sun seems to rise higher in summer and to
sink lower in winter. In summer the sun at midday is about forty-seven
degrees nearer the zenith than in winter. Within the polar circles, which
are the same distance from the poles as the tropics from the equator, the
heat of the sun is entirely withdrawn during a portion of the year, and
during another portion of about equal length the sun does not set. The
extremes of temperature, caused by the inclination of the earth's axis and
its revolution around the sun, are very great. In the northern part of
Minnesota, the temperature rises in summer to one hundred degrees, and in
winter sinks to fifty degrees below zero, giving thus an alternation of
one hundred and fifty degrees.

"In this connection you may also remember that the sun is nearer the earth
in one part of its orbit than in another part. This difference amounts to
about 3,000,000 miles. The sun also remains eight days longer north of the
equator than south of it. Our summer, therefore, is eight days longer than
the summer of the southern hemispheres, and our winters are
correspondingly shorter. These differences tend, however, to balance each
other, for while the southern summer is shorter, the sun at that time is
nearer, and while our summer is longer, the sun is more distant. Peter,
you may explain to us the effect upon temperature caused by the division
of the earth's surface into land and water."

"I learned while studying physical geography that the temperature is more
even upon the sea than upon the land. But why, I do not know."

"The smooth surface of the sea reflects heat better than the rough land:
for this reason, a larger proportion of the heat which falls upon the sea
is not absorbed, but reflected and lost, so far as the temperature of this
world is concerned. Water is also a very poor conductor of heat, and has
withal a very high specific heat. For these reasons the sea receives and
parts with heat more slowly than the land, and its absorption or radiation
causes a smaller variation of temperature. The result is, therefore, that
the sea is cooler in summer and warmer in winter than the land, and the
average ocean temperature is lower than the mean continental temperature.
The land receives heat more readily and parts with it more rapidly; the
fluctuations of temperature must therefore be greater. Hence, the
interiors of the continents have much greater extremes of temperature than
the sea-board. But of the influence of water in equalizing temperature I
shall have occasion to speak again more at length, and will pass it by for
the present. What effect, Peter, has the unevenness of the earth's surface
upon temperature?"

"The higher we ascend upon mountains, the colder we find it."

"That is, Peter, the greater the elevation of any place or country above
the sea level, the lower the temperature. Almost the whole surface of the
earth is an alternation of mountain and hill, valley and plain. One
continent has a very much greater mean elevation than another. One region
or tract of country lies sloping toward the sun, another is inclined from
it. The effect in the one case is the same as if the sun were brought more
nearly overhead; in the other case, the sun is depressed toward the
horizon. It is all the same as if the region of country were brought
nearer the equator or removed farther from it. The effects of the
curvature of the earth are obviated or exaggerated. Do clouds tend to
produce inequalities of temperature?"

"I think they must do this," answered Samuel. "Clouds cover one portion of
the earth's surface and shut out the heat of the sun, while other portions
are well exposed to the sun's rays."

"That is right, Samuel. Does any one think of another cause of inequality
of temperature?"

There was a pause. Then Mr. Hume answered: "Considering the unmeasured
cycles of the past, the gradual cooling of the earth has brought a great
change of temperature."

"And this change," continued Mr. Wilton, "has been very important for the
welfare of the human race. At the present temperature of the earth, the
coal-beds, so necessary for the culture and progress of the race, could
hardly have been formed, and at the temperature of the carboniferous
periods, when the coal-beds were deposited, the human race could with
difficulty have survived. The high temperature required to prepare the
earth for man is now no longer needed, but would prove destructive. And
this great change of temperature was doubtless caused by the cooling of
the earth.

"The result of all these agencies--the shape of the earth, its daily and
yearly motions, the inclination of its axis, the eccentricity of its
orbit, the division of its surface into land and water, the varying
elevation of its surface, and the clouds and storms that hide the sun--is
that we have great extremes and rapid transitions of heat and cold, and
every variety of climate. These changes of temperature are often painful
and, unless guarded against, dangerous. Yet, taken as a whole, can one
doubt that variety of climate and change of temperature are of advantage
to man? What weariness and lassitude a changeless temperature would
bring! How the cooler air of the night comes as a tonic after the
relaxation of the heated noonday! Who can estimate the value of our
northern winters, not alone in building up a vigorous and nervous physical
frame, but in helping the culture of men and nurturing the domestic
virtues? We might almost say that her winter evenings have been the making
of New England. But periods of heat are needed for bringing fruit and
grain to ripeness. What variety and richness of productions for the use of
man the different zones furnish! The supply of man's wants would be
comparatively meagre if we had but one zone, even though we had our choice
of the zones. But every zone is necessary for the perfection of the
temperate zones. That we may have the warmth of summer in the temperate
zones we must have the torrid zone. That we may have the tonic cold of the
temperate zones we must needs have the severity of polar winters. I do not
mean that the Creator could not devise a world that should not have these
painful extremes, yet enjoy the advantages of the temperate regions. But
that would plainly require a world constituted upon principles very unlike
those which now prevail. With God this is doubtless possible, but the
mode is to us inconceivable. But we can easily see that by the present
arrangement of things God has secured many great advantages for man--how
many and how great, we can hardly understand--and the apparent
disadvantages we cannot positively affirm to be real evils. We can safely
declare that this world is well adapted to man's necessities. But these
inequalities of temperature are modified and softened by a most
comprehensive and beneficent system of agencies by which the extremes are
prevented from becoming destructive. In this system of compensating
agencies two great divine ideas are clearly developed, economy in the
expenditure of heat and benevolence toward man. Upon this subject we are
now prepared to enter."



CHAPTER VIII.

MODIFICATION OF TEMPERATURE.


Resuming the subject where it was left the previous Lord's Day, Mr. Wilton
said:

"We saw at our last session that the most prominent and permanent features
of the earth tend to produce differences and great extremes of
temperature. These variations of temperature within due limits must be
regarded as beneficial, if not absolutely essential, to the well-being of
the human race. The different zones give the world a richer and more
varied supply of food, and finer and more varied plants and animals. The
change of seasons gives variety in the experience of life; the warmth of
summer ripens the fruit and grain, and the cold of winter tones up the
physical strength; nay, the winter's frost is a natural subsoiler,
loosening up the hard earth and promoting vegetable growth. As for man's
higher interests, no one can tell how much the world is indebted to winter
evenings, to a period of darkness longer than is needed for sleep, and a
period of cold during which the work of husbandry may largely cease.
Learning, the domestic virtues, and religion are greatly indebted to our
winters. But were these agencies which tend to produce inequality of
temperature suffered to operate without counteracting influences, the
extremes of heat and cold would cease to be genial and healthful, and
become destructive. We are now to begin the consideration of those
counteracting agencies by which the extremes of temperature are moderated.

"Let us look first at the daily fluctuation of temperature caused by the
revolution of the earth upon its axis. The rotation of the earth brings
every place by turns under the influence of the sun's rays, and in turn
withdraws it from the heat of the sun, thus producing a daily change of
temperature. How is this diurnal change of temperature alleviated?"

This was addressed to all, but no one answered. "Mr. Hume, I should be
glad to have you suggest the answer."

"There are two chief agencies," Mr. Hume replied--"first, the absorption
of heat during the day and the radiation of that heat during the night;
and, secondly, the formation of watery vapor during the day and the
deposition of dew by night."

"The first of these agencies," said Mr. Wilton, "is so plain that very
little explanation need be made. During the day, while the sun is shining
and the temperature is rising, the surface of the earth, the rocks, the
trees, and all things are absorbing heat. This heat is, so to speak, laid
up in store, ready for use in time of need. In due time the sun sinks low
and sets behind the horizon; the supply of heat is cut off and the
temperature begins to fall. Then all those objects which during the day
were laying up heat in store begin to radiate heat into the air, and by
their contact with it keep up its warmth. Commonly, the temperature falls
so low that bodies radiate more heat than they absorb before the setting
of the sun. In this process water plays a very conspicuous part. You will
call to mind what was said before about the large specific heat of water.
By means of this, water is able to store up heat in large amounts--larger
in proportion to its weight than any other substance except hydrogen gas.
The heat that is stored up during the day is given off by contact with the
air and by radiation during the night.

"But water plays a still more important part in moderating the daily
fluctuations of temperature by the process of evaporation and the
formation of dew. Call to mind what was said of the formation of vapor
when we were speaking of latent heat. Heat water to two hundred and twelve
degrees--the boiling point: it must still be heated a long time before it
evaporates. Boiling water must receive five and a half times more heat to
give it the form of vapor than to raise it from the freezing to the
boiling point; that is, about one thousand degrees of heat are required to
turn boiling hot water to vapor. The same amount of heat is required for
the formation of vapor whatever the temperature of the water from which
the vapor rises. There is only this difference--vapor from cold water is
cold, while vapor from hot water is hot. Evaporation goes on more rapidly
in proportion as the temperature rises, but vapor is formed at all
temperatures. Evaporation goes on from ice. The Alpine glaciers, or rivers
of ice, sink away several feet by evaporation from their surface during
their slow course of many years down the mountain ravines. This process of
evaporation goes on, I say, during the day, and in the formation of vapor
an amount of heat which would raise an equal weight of water through one
thousand degrees of temperature is used up.

"This vapor which is formed is not supported _by the_ air, as men commonly
suppose. It is true that clouds are held up by the atmosphere, but clouds
are condensed vapor--minute globules of water floating in the air. Vapor
is invisible. You must have noticed that steam is invisible till it is
condensed by contact with the colder air. Vapor rests upon the earth and
supports itself by its own elastic force, just as the atmosphere supports
itself. The presence of air makes no difference with the formation of
vapor, except that in a vacuum vapor forms very much more rapidly, because
no air stands in its way. But at any given temperature, in the air or in a
vacuum, the same amount of vapor rises in due time, and the same amount
can support itself. Vapor seems to circulate between the atoms of air, as
sand fills the spaces between marbles. At the temperature of four degrees
below zero vapor equal to two-thirds of an inch of water can be formed and
support itself by its elasticity; that is, the elastic force of vapor at
four degrees below zero is equal to two-fifths of an ounce per square
inch; at thirty-six degrees vapor equal to two and two-thirds inches of
water can support itself; at eighty degrees vapor equal to thirteen inches
of water can exist; at one hundred and seventy-nine degrees, seventeen
feet; and at two hundred and twelve degrees nearly thirty-four feet; that
is, vapor at two hundred and twelve degrees has an elastic force of
fifteen pounds to the square inch. Let us suppose that at sunrise the air
has a temperature of thirty-six degrees, and that as much vapor is already
formed as can sustain itself at that temperature. As the sun sheds down
his rays the temperature rises and more vapor is formed. We will suppose
that half an inch of water is evaporated. Some of this vapor will be
carried by ascending currents of air into the higher regions and condensed
into clouds, some will be carried by winds into drier and warmer regions,
yet the amount of vapor will increase during the day. We will suppose that
during the night the temperature falls again to thirty-six degrees; all
the excess of vapor above two inches and two-thirds of water will be
condensed and become dew or fog, and in this condensation the thousand
degrees of heat absorbed in the formation of the vapor will be given out
again. If vapor equal to one inch of water be condensed, heat is set free
sufficient to boil a sheet of ice water, five and a half inches in
thickness, extending over the whole region; that is, it would be all the
same as if a fire were kindled on every square rod of land hot enough to
boil during the night more than twenty barrels of ice water. In this
illustration I have supposed a larger condensation than commonly takes
place, but very much less than is conceivable. Suppose that the
temperature is eighty degrees, and that, as is possible, more than one
foot of water exists in the state of vapor. Let the temperature fall to
thirty-six degrees, and full ten inches of water must be condensed,
setting free heat which would boil four and a half feet of ice water. So
large a condensation as this never takes place in twelve hours, partly
because the full amount of vapor which might be formed is never actually
produced, and partly because the condensation of but a small part of this
vapor would check the fall of temperature and prevent farther
condensation. The supposition that I have made shows the possibilities of
this method of moderating extremes of heat and cold. Were it not for these
processes, our days would be much warmer and our nights much cooler than
they now are. By the formation of vapor the excess of heat during the day
is stored up in a latent form; that is, it is used, not as heat, but as
force, and is employed in bringing the atoms of water into new
relationship; during the night the vapor returns to its former state as
water, and the heat-force again becomes sensible heat. Thus the day is
cooled and the night made warmer.

"Ansel, have you ever heard the 'dew point' spoken of?"

"Yes, sir, I have."

"Do you know what is meant by it?"

"That point or degree of temperature at which dew begins to be formed."

"Upon what does the dew point depend?"

"Upon the amount of vapor in the air."

"That is right, Ansel. If at any time the full possible amount of vapor
should exist, any diminution of the temperature must, of course, cause
dew to be deposited. Do you know, Ansel, how to ascertain the dew point at
any time?"

"No, sir, I do not."

"There is a beautiful instrument known as Daniell's Hygrometer which shows
the dew point as a thermometer shows the temperature. But any one can
easily determine the dew point without a special instrument for that
purpose. Pour warm water into a glass pitcher or goblet whose outer
surface has been wiped perfectly dry, and polished. Into this set a common
thermometer. Cool down this warm water by dropping into it small pieces of
ice, and notice carefully when the polished glass begins to be dimmed as
if it had been breathed upon. When that begins to take place the
thermometer will show the dew point. In this manner we can determine the
amount of vapor in the air, and by estimating the probable temperature of
the night judge of the probability that dew will fall."

"I have noticed some things," said Peter, "about the formation of dew
which I do not understand, and I wish very much to ask about them."

"I should be glad to hear your questions, and will answer them if I can."

"I have noticed that dew falls on clear nights, but not very often on
cloudy nights. I don't see why that is so."

"Have you ever noticed whether cloudy nights or clear nights are the
warmer?"

"Cloudy nights are commonly warmer, I think, but I never could see the
reason for that, either."

"Can you tell why a newspaper spread over a tomato vine keeps the frost
from the vine?"

"Because the frost comes upon the paper instead of the vine, of course."

"But why do you say, of course? Why does not the dew--for frost is nothing
but dew frozen as it forms--come upon the under side of the paper?"

"How could the dew fall upon the under side?"

"That is just the point which we need first of all to understand. Men
commonly speak of dew as if it fell. I don't know but I have spoken of the
falling of dew in this lesson. But dew does not fall at all. The vapor
simply touches some cold object, and is condensed upon it. The vapor by
its elasticity presses against the cold body, and the process of
condensation continues until either the body is warmed by the heat set
free so that its temperature rises above the dew point, or till the vapor
is so far exhausted that the dew point falls below the existing
temperature. Dew is formed upon the upper surface and not upon the under,
because the upper surface is cool and the under surface is warmer. Beneath
the paper spread over the tomato vine, the earth is radiating heat and the
paper is radiating it back again. If the paper were not there, the heat
would be radiated into space and not returned again. The vine would soon
radiate away its little store of heat, its temperature would sink, below
the dew point, and dew or frost would be deposited upon it. The under
surfaces of objects are kept warm by the radiation from the earth. In the
same manner clouds are wrapped around the earth and keep it warm by
radiating back its radiant heat. Dew is not formed on cloudy nights,
because they are warmer: the clouds throw back the heat which otherwise
would be lost in open space."

"I never knew before," said Peter, "that clouds were of any great use
except to send down rain."

"We shall see in the course of our lessons that clouds are of very great
use in warming the earth in other ways, as well as by serving as blankets
and radiating back the heat which otherwise would escape."

"I wanted also to ask why dew falls--I mean, is formed--on grass and
leaves of plants while stones are dry."

"I will answer your question by asking another. Did you ever see barefoot
boys running in the cold dew stop and stand upon a stone or rock to get
their feet warm?"

"Oh yes, sir; I have done it myself."

"Why did you stand upon a rock?"

"Because I had learned that the rocks would be warm."

"I think that answers your question. The rocks and stones are warmer than
the grass and the leaves. The blades of grass and the leaves are thin and
pointed and rough, and have a very large radiating surface. They have but
little heat, and that little they part with rapidly. The rocks and stones,
on the other hand, are bulky, and contain a much larger store of heat,
their radiating surface is comparatively small; only one side is exposed,
the other being covered by the warm earth, from which they are drinking in
heat almost as rapidly as they lose it. They therefore do not lose heat
enough to sink their temperature to the dew point.

"So much, then, for the means employed to moderate the changes of
temperature from day to night and from night to day. But upon the
sea-coast and upon certain islands of the sea another agency is employed.
Will some one suggest what this agency is?"

No one else answered, and finally Mr. Hume said: "I suppose, of course,
that you refer to the land and sea breezes?"

"This is what I had in mind. During the day the land is warmer than the
sea, and the breeze from the sea blowing upon the land cools the air.
During the night the land radiates its heat more rapidly than the water,
and soon the sea becomes the warmer. Then a breeze springs up in the
opposite direction; the cooler air of the land flows out upon the sea. By
this means the air upon the land and the air upon the sea are daily
commingled, thus securing a more even temperature upon the land. This
softens the extremes of daily temperature. I make only this brief
reference to the land and sea breezes, because in another connection we
shall examine the general subject of winds and their influence in the
equalization of temperature.

"The result of all these influences is that the changes of temperature
from day to night and from night to day, while not inconsiderable, are by
no means destructive, and in many cases are no greater than is refreshing
and agreeable. These agencies remind us every day of the wise provision of
the Creator for the well-being of his creatures. 'Day unto day uttereth
speech and night unto night showeth knowledge. There is no speech nor
language where their voice is not heard.' This care for the earthly
well-being of men is but a type of his care for their spiritual happiness.
The plan of salvation, and the ways of divine providence working in
accordance therewith, are more wonderful both in their means and their end
than the greatest of the works of Nature. If while we study the natural we
forget the supernatural, we commit the greatest mistake: we pass by the
greater to examine the less. The natural is valuable only as it leads to
the spiritual."



CHAPTER IX.

THE MINISTRY OF SUFFERING.


"You must know, Mr. Wilton," said Mr. Hume, "that my mind is full of
objections, whether I speak them out or keep silence. I have looked so
long upon one side only that I find it hard to look upon other sides also;
and if there be a Satan, as the Bible teaches, I think he must be
marshaling all his legions to overwhelm me by the force of his impetuous
assaults. I cannot disguise the fact--I do not attempt to disguise
it--that my mind is not at ease. It used to be at rest, at least
comparatively so--not happy, yet not agitated and distressed. My heart was
not satisfied, but I believed that my position of unbelief was logically
impregnable. But I confess it, my unbelief has of late been shaken. I am
no longer contented. How I came into this state, I do not know. I am
certain that my present unrest was not produced by the force of arguments
which I had heard. It seems to me as if it sprang up uncaused. The old
arguments which I have thought impregnable do not now satisfy me. Why, I
cannot tell. I think this statement is due to you to explain my position
in your Bible class, and also to prepare the way for a question which I
wish very much to propose. I have no objections to make to the marks of
wisdom and benevolent design seen in the works of creation which I cannot
myself answer and remove. Good-will and goodness to the inhabitants of the
earth lie on the very surface of things; or, if I go beneath the surface,
I find them no less manifest in the profoundest and subtlest arrangements
of the universe. If I say, 'This is all the work of chance,' my very
language is self-contradictory and looks me out of countenance, for the
very idea of chance is the opposite of wise and orderly arrangement. The
difference between design and chance is that the one works by orderly
arrangements adapted to the accomplishment of a foreseen end, while the
other shows itself in chaotic disorder, with no adaptation to the
accomplishment of a purpose. To say that a universe like this, filled in
every part with order and beauty, with subtle and unseen elements and
agencies working out into the boldest relief in the accomplishment of
beneficent ends, all minute elements blending in the sublime sweep of the
universal plan,--to say that such a universe is the work of chance is to
use language without meaning.

"If I deny a providential plan in the creation and government of the
world, and attribute to brute matter a nature that, by its own inherent
force, spontaneously develops into all these contrivances of use and
beauty, I see that the wisdom of the whole universe is concentrated in the
nature of matter, and, if it be possible, infinite subtlety of design is
doubly manifest. To create a machine which, upon its elements being thrown
into an indiscriminate pile, shall arrange itself, adapt part to part, and
set itself in motion; which shall repair all its breaks, produce other
machines as curious as itself, and thus reproduce itself and perpetuate
its existence for ever--that would certainly be the acme of intelligent
design.

"Or if I go farther and deny a Creator, ascribing to the universe an
eternal, uncreated existence, I see that I only entangle myself in a
complication of difficulties. I find myself standing face to face with the
best-established facts of geology. If the fact that the animal tribes
which inhabit the earth, and especially the human race, had a beginning be
not well established, then no fact in geological science can be reckoned
as fixed. Geology has overturned the idea of an infinite series of
generations of animals and men. Nor do I see that I gain any advantage or
give any explanation of the universe by attributing to matter everything
which others refer to an intelligent and almighty Creator. The distinction
between mind and matter is that mind is endowed with intelligence and
will, while matter has neither intelligence nor will, but only blind
forces, blind attractions and repulsions. If I attribute the order,
beauty, design, and benevolence of the universe to mere matter, I clothe
matter with the attributes of spirit. In fact, I only set up another God
and ascribe to the universe a true divinity. I make myself a kind of
pantheist, investing all matter with the attributes of mind and spirit.
All this I have pondered over for many a day, and I cannot deny that a
belief in an intelligent Creator of the universe is logically more
satisfactory. But there is one question which confronts me at every turn.
I suppose that I might at length work out an answer for myself and that I
should now see the explanation if all my thinking for so many years had
not been upon the other side."

"I am afraid that I shall not be able to give you satisfaction," replied
Mr. Wilton, "but I shall be glad to hear your question. I can at least
appreciate your state, and sympathize with you in your groping and
struggling. I am glad that you are walking the road you have just
described. You say that you do not know what has brought you to your
present state. I can easily tell you: your experience at this point is not
singular; I think the Holy Spirit of God has been leading you and has
brought you to your present position. I trust in God that he will lead you
still farther. You have great cause for thankfulness and great cause for
trembling. Let me caution you: be careful how you treat the divine Spirit;
walk softly; be honest, sincere, and simple-hearted as a little child.
'Except a man become as a little child, he cannot see the kingdom of
God.' Above all things, be sincere and straightforward. Deal truly and
frankly with the Spirit. If you will only be honest and frank,--honest and
frank to yourself, honest and frank to all men, honest and frank with
God,--God will soon give you cause to praise him and love him for ever and
ever. But what is the question which you wished to propose?"

"My difficulty is this: Along with the many arrangements for conferring
enjoyment and promoting the well-being of man are other arrangements for
suffering. Man is made as capable of suffering as of enjoyment, and there
are appliances provided which are certain to inflict that pain of which
man is capable. How is this provision for suffering in man and in all
sentient creatures consistent with the benevolence elsewhere shown? How
are we to combine these two sets of arrangements in our thinking?"

"A full unfolding of the ministry of pain in the good providence of God
would lead us entirely aside from our course of study."

"But for me," said Mr. Hume, earnestly, "it would be not at all aside; for
if I can once see that the provision for suffering made in the
constitution of man and of Nature is not repugnant to the idea of a wise
and good Creator and Disposer of human affairs, I will admit whatever you
shall have to say afterward, and I shall feel that the gospel of Christ
comes to man and comes to me with a moral force which ought not to be
resisted. I know that I have no right to come into your class and ask you
to turn aside from your course of study, and the gospel certainly owes
nothing to me, yet I do hope you will give the opinions which you hold
upon this subject, if you have formed any positive opinions."

"I am sure," exclaimed Peter, "that we shall all be very glad to have you
spend the time of this lesson in speaking of this subject."

"But how would it please you if my talk upon the ministry of pain should
prove to be very much like a sermon?"

"I think we like your sermons. I know that we were never so much
interested in them as now."

"Very well, then; I will give you, as Mr. Hume says, some of my
conclusions touching this matter of pain and suffering; and if my opinions
are not satisfactory or do not cover the facts in the case, it will not
be because I have given the subject little thought or have had little
experience of suffering. The Lord has led me by a rugged road; he has
given me tears to drink and mingled my cup with weeping. But for this I
thank him, and I expect, when I shall look back from the life to come upon
my earthly course, to see my days of pain and grief shining more brightly
than the hours of radiant sunshine.

"First of all, then, I believe that with the clear exhibition of
benevolent design which we see in this world we ought not to doubt the
goodness of the Creator, even if we can give no rational explanation of
the suffering which abounds. We ought not to believe, we cannot believe,
that the Creator's own attributes are self-contradictory and antagonistic,
that the same infinite Being is both good and evil, partly benevolent and
partly malignant. If God is good at all, he is wholly good. Nor can we
believe that a good being and an evil being--God and Satan--hold joint
sway over the universe and co-operated in the work of creation, and that
the good is to be ascribed to the one, and the pain and suffering to the
other. Whether we can explain it or not, we must believe that there is a
good reason for the existence of suffering; unless, indeed, we count the
infliction of pain the chief end of the creation, and refer the happiness
which men enjoy to some incidental arrangements not contemplated as
important in the work of creation. But no sane man can think that this
world is the work of a demon seeking to fill the earth with groans and
wretchedness. Our consciences and our reason alike require us to believe
in the supremacy of goodness.

"In presenting my views, I of course cannot attempt to prove everything
from the beginning: I must take some things for granted between us. We
must start with the admission that there is a God, and that he is a
righteous, moral governor. We must at least believe what Paul declares to
be needful: 'He that cometh to God must believe that he is, and that he is
a rewarder of them that diligently seek him.' We must also believe our own
consciences when they testify that men are responsible, free moral actors,
and that sin and guilt are not false notions arising from diseased and
morbid mental conditions, but realities, true ideas which arise in the
mind when it works as God designed. Do you freely admit these points of
belief, Mr. Hume?"

"Yes, sir; I could not ask you to prove every point touched upon in the
argument, for that would require half a score of volumes, nor will I deny
the testimony of my own conscience that there is a God, and that men are
rightly responsible to him."

"Starting, then, with these fundamental principles, we will look first at
the provision made for physical pain. Men and, I suppose, all living
creatures are created with the capacity of suffering. The same nerves of
sensation which if excited naturally give rise to pleasure may be excited
unnaturally and inflict pain. But why not endow living creatures with
nerves of sensation which could experience pleasure, but could not feel
pain? Is this possible? Perhaps so, but no man can affirm it with
certainty. I do not think that any man can clearly conceive such a thing.
To us the capacity of enjoying and that of suffering seem inseparable. But
there is no need of insisting upon this point, for the capacity of feeling
pain is a most benevolent provision of the Creator for the benefit of
living creatures. It is designed to save life and limb. Pain is the
sentinel set to guard the outposts of the citadel of life. If there were
no pain, men would thrust their hands into flames without knowing it. They
would indulge in all manner of destructive excesses, and no sufferings
would warn them of danger. They would drink poison, and no pain would bid
them make haste to take the antidote. Tear men limb from limb, hew them in
pieces with the sword, and no painful sensations would rouse them to
self-defence. Without this benevolent provision of pain the race of man
could hardly be saved from extinction. How much more would this be true of
the animal tribes, which are wholly dependent on instinct for guidance and
impulse to action! We accordingly find pain possible in those parts of the
body where pain can subserve the purpose of protection; elsewhere no
provision is made for pain. Nerves of sensation abound in those parts
which require especial care or are especially exposed. The skin is
exposed, therefore the skin is well supplied with nerves. The parts
beneath the skin are less exposed, and are injured only by first wounding
the skin; they are therefore less sensitive. The heart, though so very
important, is almost insensible to pain, because the capacity of
suffering at that point would confer no protection. The eye is delicate
and requires the greatest care, and to secure that needed care the Creator
has made it delicately susceptible of pain. The sole of the foot, as its
work demanded, was made capable of bearing the roughest usage, and hence
the sole of the foot is but little supplied with nerves of sensation.
Still farther, when on account of injury any part of the body requires
unwonted care, provision is made that the injured part shall become
especially sensitive. A bone when well and sound may be cut or sawed
almost without pain, but when the bone is injured it becomes inflamed and
feels pain most keenly. When a limb for the sake of its own safety ought
to be kept quiet, Nature makes it painful to move it. For the benevolent
object of preserving life and guarding the well-being of living creatures
pain is given. The provision for pain shows the presence of danger, the
liability of receiving injury, and the kind design of putting men on their
guard. It is the automatic guardian of our happiness. This is all that I
have to say about bodily pain.

"Mental suffering and pain of conscience are designed, first of all, to
subserve the same purpose. The sense of guilt when a man commits a wicked
act is designed, first, to lead him to repentance. It is the divine alarum
placed within the soul to remind men that they have done evil and received
moral damage which must be repaired. It is the moral goad which pricks men
to warn them to turn from wickedness. If evil-doing were as pleasant as
well-doing, men would see no difference between right and wrong; all moral
ideas would be subverted and the glory and beauty of man would be trailed
in the dust.

"But a guilty conscience continues to trouble wicked men after the day of
repentance has passed; Remorse indeed seems to rise up with preternatural
power when Mercy has withdrawn for ever from the sight of Hope. What is
the meaning of this? It means that which we admitted in the beginning,
that sinners are guilty in God's sight, that guilt is a real thing and
deserves punishment, and that God, the holy and righteous King of men,
does actually punish the guilty. God is holy and abhors sin. Remorse of
conscience is the shadow of the Creator's frown, the voice of his eternal
indignation echoing and re-echoing in the soul of man. It is the divine
wrath penetrating the human spirit and making itself felt. As the holy God
abhors sin for ever, the wicked must expect to feel that abhorrence for
ever. He who puts himself into a rebellious position toward his Creator
must stand in that unnatural attitude guilty and suffering. We can
conceive that this should be otherwise only by subverting the foundations
of the moral world. Beings created in the image of God, created with a
conscience and moral affections, created with moral freedom, can attain
blessedness only by aspiring to heavenly things and becoming God-like. If
they break away from the divine will and order, they must suffer the
divine frown, they must feel that frown. How can God make his frown felt
except by looking pain, so to speak, into the sinner's conscience?

"But this whole subject of pain and suffering derives a double
significance from the fact that the human race is a fallen race, alienated
from God by wicked works, yet under a merciful dispensation in which they
are called to return to obedience. There is no moral quality good and
beautiful to our eyes or pleasing to God in which men are not altogether
lacking, and what is still worse, men grow in evil; their last state is
worse than the first. There is no healing power in the man which can
renovate his heart and bring him back to holiness. It would seem as if
some satanic power were hurrying the human race along the road to ruin. If
men are to be saved, it must be by a force of renovation outside of
themselves, which shall reverse the evil bias of their nature. You say
that the world seems fitted to develop man's capacity for suffering, and
that this appears to be as much a part of the divine plan as the
impartation of happiness. What, think you, would be the result if the
human race were planted in a world where nothing could give pain, where
everything would afford gratification? What, Mr. Hume, do you think the
effect would be upon creatures such as we all know men to be?"

"I hardly dare answer with the little thought I have given to the subject.
I would rather listen than speak."

"I have noticed," exclaimed Ansel, "that those boys who have everything
done to suit them at home are the most unmanageable in school and the
most disagreeable to play with."

"Picture to yourselves," continued Mr. Wilton, "a man who from childhood
should have nothing to suffer, no pain or weariness or hardness to bear.
From childhood he has no bodily pain, and the comforts of life are so
carefully and bountifully provided that he receives no unpleasant
sensation. Winter never chills him, summer never heats him. His slightest
wants are all anticipated. All his sensations are pleasure. Let the same
be true of his mind. His will is never crossed; whatever he wishes is
given him; there is no call for self-denial or self-control or abstinence
or patience. He feels no pressure of need spurring him to exertion. His
whole life is enjoyment. His very body would grow up, not strengthened and
compacted for exertion, but fitted only for the softness of indolence and
ease. His will would be the selfishness of self-will rather than an
intelligent, reasonable self-control. There would be no tenderness and
power of love, no endurance and patience in labor, no strength of moral
purpose under temptation, no self-denial and self-sacrifice of love for
the good of others or for the attainment of a higher blessedness, no
faith in God nurtured in darkness and trial. We should have a mushroom
growth of luxurious tastes and indolent ease, impulsiveness and
impatience, strength only in selfish, passionate self-will and rampant,
luxuriant vices. No other result would be possible with creatures like us.
Strength is developed only under circumstances which call for the exercise
of strength. A certain hardness and hardihood of living is needed to
develop a manly body. Resolute intellectual exertion in the face of
difficulties is demanded to educate the mental faculties. An earthly life
not wholly satisfactory is needed to awaken in faithless men a longing for
a better land. We may look upon the sufferings of this world, taken as a
whole, as an expression of God's displeasure at sin. How very much is such
an expression needed! If life were nothing but pleasure, how completely
men would forget sin and duty and God and heaven! All the varied
experiences of joy and sorrow, of good and ill, of trial and triumph, are
needed for man's spiritual discipline. I think you will bear me witness
that the noblest, sweetest, most beautiful characters are found in those
who have drunk the cup of sorrow to the dregs."

"I cannot deny it, Mr. Wilton. There is old Deacon Smith. We all know
something of his history, I suppose. He was a poor boy; when he was twelve
years of age his father died, and his mother died four years later. But he
worked his way, first to a good education, and then to an honorable
position and ample fortune. Then the dishonesty of a partner brought him
back to poverty too late in life for him to recover himself. Now in his
old age he works for a small salary in the office of another. But he is as
cheerful and as grateful as if he had all that heart could wish, and had
never in his life suffered a pang. I think he verily believes that
everything which has befallen him has been an expression of God's love for
him. He sheds no tears except for the griefs of others. I think he truly
rejoices with those that rejoice and weeps with those that weep. As for
faith in God, I suppose he would go into a lion's den as calmly as did
Daniel. If every professor of religion were like him, I am sure that
nobody could say a word against the gospel. I freely confess that Deacon
Smith's character has affected me more than all the arguments I have
heard in favor of Christianity."

"As to that, Mr. Hume," replied Mr. Wilton, "we have both of us,
doubtless, seen men who would hate a man the more bitterly in proportion
as he should show himself Christlike. And as to every church-member being
like Deacon Smith, we could hardly expect such a character to be nurtured
in a day or a year. Deacon Smith has become what he is by a lifetime of
severest spiritual discipline and patient endeavor. Such characters are
wrought out only by a discipline of every form of trial. This world is
constituted as it is for the purpose of giving just such a discipline of
effort and patience.

"This explanation brings us, however, only to the vestibule of the great
mystery of suffering in the work of recovering man from the Fall. The
Captain of our salvation, who put himself in man's place and took upon
himself all human conditions, was made perfect through suffering. The full
preparation for his work as the Saviour of man called for a discipline of
pain. I shall not attempt to explain this experience of Christ, but
salvation brings the believer into a state of profoundest and most
mysterious union with Christ. The believer must walk in the footsteps of
Jesus. As Christ first came into a condition of sympathy with man, so must
man come into a condition of sympathy with him. The believer must share
and repeat, in a feebler way, of course, the experiences of the Lord
Jesus. He must fill up that which is behind of the sufferings of his
Saviour. By this union with Christ in the discipline of pain the Christian
is prepared for a union of blessedness. 'If we suffer, we shall also reign
with him.' How broad and deep this union of the believer with Christ may
be, I cannot tell. I am not able to measure this idea. It seems to me like
one of God's infinite thoughts, revealed in its dimness to overawe the
souls of men by its shadowy sublimity--seen only enough to suggest how
much vaster is that which remains unseen--an iceberg, one part standing
out and nine parts sunk in the unfathomed sea. It is a thought to be felt
and experienced rather than weighed and measured by human logic. This is
all that I have to say upon this subject. Do these views commend
themselves to you, Mr. Hume?"

"I do not know," was the reply; "I want to revolve the subject in my own
mind. I have received some new ideas, but I judge that a man needs
experience in this matter as well as thinking. If I had Deacon Smith's
experience of life, I could form a better opinion. As much as this I can
see to be true--that provision for bodily pain is a safeguard to the
happiness and life of men, and that a world which should anticipate every
human want, leaving nothing to be struggled after and nothing to be
endured, would have a disastrous influence upon human character. I will
admit that the provision for pain is wise and good."

"One other point," continued Mr. Wilton, "we ought to notice before
leaving this subject. The word of God says, 'We know that all things work
together for good to them which love God,' but it says no such thing of
those who do not love him. The afflictions of this life work out for the
righteous 'a far more exceeding and eternal weight of glory.' The ministry
of pain is a ministry of love only to those who submit to Christ. To those
who kick at God's mercies the best blessings turn to evils and curses; to
the faithful in Christ the greatest griefs and calamities become choice
blessings. A submissive heart and the agency of the Holy Spirit are
needed to sanctify pain. It is a great mistake to think that all men are
made better by afflictions. Only the few get good from the discipline of
life. With many persons troubles only stir up the worst passions till they
rage like caged tigers."

"This last remark, Mr. Wilton, has thrown a flood of light upon this
subject. But it seems strange to me to find myself saying this. I see how
it is that so large a part of the pains of life is found in the end to
accomplish no good. The evil remains evil. Do you think that my long trial
of doubt and unrest and pain of heart can ever be blessed to my good?"

"That it can be so blessed to your good and to the good of many others I
have no doubt; but whether it will be, I cannot tell. That depends upon
yourself, upon your coming through Christ to God as your heavenly Father.
It is my earnest prayer that from your unrest of spirit deep peace in
Christ may break forth; and many others unite in the same."

"I certainly hope," said Mr. Hume, "that my life may not come to nothing.
It seems as if something better than a few years of mingled pain and
pleasure, overshadowed by most painful doubt and darkness and followed by
a plunge into nothingness, must be possible for me."

"God give you grace," said Mr. Wilton, earnestly, "to forget the things
which are behind, and reach out your hands toward the worthiest destiny!
But remember that there is a destiny more terrible than to cease to be,
there is a death deeper and darker than the grave.

    'There is a death whose pang
      Outlasts the fleeting breath;
    Oh, what eternal terrors hang
      Around the second death!'"

Mr. Wilton did not think it best to attempt to draw out Mr. Hume farther
at that time. He saw that he appeared to be under the guidance of the Holy
Spirit, and hoped that he would soon experience the new birth by which old
things pass away and all things become new. He knew that time is an
element even in the operations of the Spirit, and he feared to shake the
bough too roughly lest the fruit should fall untimely only to wither in
his hand. Happily, the superintendent's bell brought the conversation at
that point to a natural conclusion.



CHAPTER X.

TRANSPORTATION OF HEAT.


"To-day we come to that subject which we should have looked at a week ago,
if that I hope not unprofitable discussion of the uses of trials and the
ministry of pain had not prevented. We must now examine the arrangement
for softening the rigors of winter and toning down the heat of summer. The
general principle is that in summer the earth receives an excess of heat,
while in winter the opposite is true. These extremes are mitigated by
transferring heat from summer to winter. How is this accomplished? Any one
who has thoughts upon this subject may answer."

"I have some thoughts," said Ansel, "but whether right or wrong, I cannot
tell. I should think heat might be carried from summer to winter in the
same way as from day to night."

"What are some of those means for transferring heat which seem to you to
operate the same in the annual as in the daily changes of temperature?"

"One is the absorption and radiation of heat, and another is the
evaporation of water and the condensation of vapor."

"You are right," said Mr. Wilton. "The effect of these operations in the
equalization of the annual extremes of heat is in no wise different from
their effect upon the temperature of day and night, but from summer to
winter their effect is vaster and more impressive. During the summer, sea
and land, and 'all that in them is,' are receiving heat and rising in
temperature. The heat of summer penetrates and warms the earth nearly a
hundred feet in depth. Into the sea heat penetrates still deeper. How vast
the amount of heat required to warm the whole surface of the earth and sea
to such depths! By withdrawing so much heat from active use the intensity
of the summer temperature is softened. During the colder months the land
and sea slowly radiate their heat. We can hardly over-estimate the effect
of this alternate absorption and radiation of heat. So great is the
effect of this stored up heat that the sea and the great lakes never
freeze even in the coldest winter weather, except in the polar regions,
and the temperature must fall far below freezing and continue for a long
time below the freezing point before the earth begins to freeze. The great
bodies of water, remaining always at a temperature above thirty-two
degrees, are especially important in warming the wintry air. In the
coldest weather they seem like steaming caldrons throwing up their warm
vapor. It is the absorption and radiation of heat alone which prevent the
temperature of the atmosphere from rising or falling suddenly to the
highest or lowest point possible. The sun breaks forth in all its splendor
at noonday in summer: what if the sun were to remain stationary, shining
thus in his strength for days and months? Everything would be consumed
with heat. But why do not the glowing rays of the sun raise the
temperature at once to the highest possible point? Because the earth and
sea and every object upon the earth absorb the heat, storing it up and
holding it in reserve. On the other hand, when the sun sets and his heat
is withdrawn, why does not the temperature fall suddenly to the lowest
possible point? Because the heat held in store is slowly radiated and the
change of temperature rendered gradual.

"In this work of absorbing and radiating heat every object, earth, air,
and sea, does its appropriate share. But water stands chief, and performs
the largest service. Its high specific heat enables it to hold in store
the largest calorific treasure, and causes it to change its temperature
more slowly.

"The formation and condensation of vapor also operate in the same manner
as in the transitions of day and night. During the summer the higher
average temperature makes it possible for a much larger amount of vapor to
be formed than in winter. You remember that at eighty degrees vapor equal
to thirteen inches of water can sustain itself, while at thirty-six
degrees the elastic force of vapor is equal to the pressure of only two
inches and two-fifths of water, and at four degrees to three-fifths of an
inch. If the mean summer temperature at any place were eighty degrees, it
would be possible for more than one foot of water to be held in the form
of vapor. In the formation of this vapor heat would be consumed
sufficient to boil more than five and a half feet of ice water. If the
mean winter temperature at the same place be thirty-six degrees, more than
three-fourths of this vapor must be condensed and give out its latent heat
to warm the air. It is not to be supposed that the full amount of vapor
which can support itself does commonly exist, but the difference between
the average amount of vapor in summer and in winter must be very great. I
suppose this difference often amounts to four or six inches of water. If
we suppose it to be four inches, an amount of heat is transferred from
summer to winter sufficient to boil twenty-two inches of ice water. In
estimating the effect of this we must consider that this heat is not given
out gradually and regularly for three months, but whenever there is a
sudden fall of temperature vapor is condensed, latent heat becomes
sensible, and the suddenness and intensity of the fall are diminished. We
need also to bear in mind that every open body of water is sending up its
clouds of vapor constantly. The open lakes, and especially the sea, are
like a seething caldron; and thus immensely more vapor is condensed during
the winter months than is brought over from summer to winter. Much of the
vapor formed in winter is to be set to the account of summer, for it is
the summer's heat absorbed by the water, which maintains its temperature
and enables it to throw up such clouds of vapor, even in midwinter. But
this comes in more properly at another place, and we will leave it for the
present.

"There is another transition experienced by water by which heat treasured
up in summer is made available for softening the rigors of winter. Who
will suggest it?"

"It is the freezing of water," said Mr. Hume. "In the process of
crystallization one hundred and forty degrees of latent heat become
sensible."

"And this," continued Mr. Wilton, "is no inconsiderable matter. Every
pound of water frozen upon the surface of our lakes and rivers, every
pound of water frozen in the wet earth, every pound of water frozen as
snow or sleet in the air, gives out as much heat as would boil an equal
amount of water at seventy-two degrees. Have you never heard of setting
tubs of water in cellars to keep vegetables from freezing?"

"I have," replied Peter. "I visited my grandfather two years ago, and his
cellar sometimes froze. I asked him why he put tubs of water in his
cellar, but he could not tell me, only he said that he knew that tubs of
water in his cellar did keep his vegetables from being nipped with the
frost."

"Can you tell us, Peter, why tubs of water set in a cellar should have
this effect?"

"I suppose that when the water begins to freeze it begins to give out its
latent heat."

"That is one part of the reason. The water is drawn from the well at
perhaps fifty degrees; it must lose eighteen degrees of heat before it
begins to freeze, and all the heat which the water loses the air of the
cellar gains. And then, as you said, as soon as the water begins to freeze
latent heat begins to become sensible. Every pound of water frozen sets
free heat enough to raise a pound of water through one hundred and forty
degrees. But why do not the vegetables begin to freeze as soon as the
water?"

"I don't know."

"Water holding salt or other minerals in solution freezes at a lower
temperature than pure water. For this reason the juices of vegetables and
fruits and the sap of trees may be cooled below thirty-two degrees
without freezing. On this account the water set in cellars tends to
prevent vegetables from freezing; the water begins to freeze at thirty-two
degrees, while potatoes and turnips may be cooled a little lower than
thirty-two degrees without harm. In this manner the buds of trees are
sometimes warmed and protected by the coating of ice which forms around
them. The drops of water, falling through the sleety air, touch upon the
twigs of trees and freeze upon them, an icy coat embracing them all
around. In freezing, the water gives out one hundred and forty degrees of
heat, a part of which goes to the air and a part to the twig."

"This reminds me," said Ansel, "of what the Irishman said on being told
that snow contains heat, that 'it would be a blessed thing for the poor if
one could tell how many snowballs it would take to boil a tea-kettle.'"

"It might be difficult to use snowballs to boil the tea-kettle, but the
heat given out in the formation of the snowflakes is doubtless employed
quite as usefully for the poor as if used in preparing their tea. You have
all noticed that before a snow-storm, or perhaps during the early part of
the storm, the temperature generally becomes milder, and you have often
heard the remark, 'It is too cold to snow.' Men have learned that the
coming of a snow-storm is attended by a warming of the air. This popular
impression is philosophical, yet few understand its philosophy. A foot of
snow falls, equal to two or three inches of water. In the condensation of
the vapor which formed this snow one thousand degrees of latent heat
become sensible, and then in the congelation of the clouds into snowflakes
one hundred and forty degrees of heat are evolved. This softening of the
rigors of winter is, I think, as great a blessing to the poor as the
heating of the tea-kettle. Let us make an estimate of the amount of heat
set free in the production of one great snow-storm. Two feet of snow
falls, equal, we will suppose, to five inches of water. In the
condensation of the watery vapor one thousand degrees of heat are evolved,
and in the congelation one hundred and forty degrees--an amount of heat
which would boil three feet of cold spring water. In every square mile
there are 27,878,400 square feet, and a square mile of water three feet in
depth would contain 83,625,200 cubic feet. The production of such a
snow-storm sets free for every square mile of surface heat which would
boil more than 80,000,000 of cubic feet of spring water. Such a storm
sometimes extends over a region of country a thousand miles square, that
is, over a million of square miles. In the production of one such storm--a
very heavy and extensive storm, I have supposed--heat is generated which
would boil eighty millions of millions (80,000,000,000,000) of cubic feet
of spring water--an amount altogether too vast for our comprehension. To
accomplish this result by combustion would require more than 500,000,000
of tons of anthracite coal--an amount at least three times as great as the
yearly product of all the coal-mines of the world. And this is but one
heavy storm. The amount of rainfall in the United States may be thirty-six
inches or forty or forty-five inches. Supposing the average rainfall of
the whole earth to be twenty-four inches--an estimate very far below the
truth--we have this result: There are, in round numbers, two hundred
millions of square miles of surface, more than five and a half
quadrillions (5,575,680,000,000,000) of square feet and more than eleven
quadrillions of cubic feet of water. The condensation of this amount of
vapor would boil more than sixty quadrillions of cubic feet of ice water.
One pound of anthracite coal burned under the most favorable circumstances
will boil sixty pounds of ice water. To boil sixty quadrillions of cubic
feet of ice water would require sixty quadrillions of pounds of
coal--thirty billions of tons--not less than twenty-five tons to every
inhabitant of the globe. At this rate a very few years would exhaust the
coal-fields of the world. Calculations like these are useful in showing
upon how stupendous a scale the Creator carries on his operations. But we
must remember that these works are carried on, not to amaze men, but to
benefit them. The works go on silently and unseen, challenging no
attention from fools, receiving no thought except from the patient student
of Nature, and eliciting no thankful recognition save from a few reverent
worshipers.

"But I have been led away from a point which I had in mind. While
considering the effect of heat in expanding bodies, I reminded you that
water presents a marked peculiarity, and promised to speak of it more
fully. This is the place for us to look at this singular and beautiful
peculiarity of water. What is the general principle touching the effect of
heat upon bodies?"

"Heat expands bodies and cold contracts them," answered Ansel.

"Water both illustrates this rule and presents some very interesting
apparent exceptions. It contracts by cold like other bodies till it
reaches the temperature of thirty-nine and a half degrees; it then begins
to expand, and expands regularly till it falls to thirty-two degrees; at
that point it freezes, and in freezing it expands at once about one-ninth
of its bulk. If the cooling process be continued, the ice produced
contracts like any other solid. This peculiarity of the interrupted and
unequal expansion of water is of the utmost importance in the affairs of
our world. Consider the result if the water were to contract by cold as do
other bodies down to the freezing point and below it. Water is cooled from
the top by contact with the cold air. As the upper film of water cooled it
would sink and a new stratum be brought to the surface; that in turn would
be cooled and sink, and thus the cooling process would go on with the
utmost rapidity till the whole body of water should be reduced to the
freezing temperature. Then congelation would begin, and the first
particles of ice formed would sink to the bottom, and as fast as the water
became frozen at the top the ice would sink. In this manner a solid body
of ice would be formed at the bottom of our lakes and rivers, while the
surface would remain unfrozen in contact with the cold air till the whole
body of water became a compact mass of ice. Great lakes turned to solid
ice would not be thawed during the whole of the summer, for the water
warmed from the top would not sink, but would form a warm stratum of water
upon the surface, while, below, the solid ice would lie hardly feeling the
summer heat. Nay, more; in the higher latitudes it would seem as if the
very ocean must be turned to solid ice, never to be melted till the end of
time. By the singular expansion of water below thirty-nine and half
degrees and its great expansion in congelation, these disastrous
consequences are prevented. Our lakes are cooled even in winter only to
thirty-nine and a half degrees; below this temperature the colder water is
lighter and remains upon the surface; ice floats upon the surface. The top
becomes ice, but the great mass of the water remains at thirty-nine
degrees, and the inhabitants of the waters live on unharmed. Spring comes,
and the ice, being upon the surface, is soon melted, and the unbound waves
begin again to ripple forth their unconscious joy."

"Do you look upon this irregular expansion and contraction of water,"
asked Mr. Hume, "as a real exception to the rule that heat expands
bodies?"

"Not at all. In freezing, a new force comes in and asserts itself--the
force of crystallization; or, more exactly, as the force of heat
diminishes the force of crystallization becomes predominant, and throws
the atoms into new positions and new relationships. To this new
arrangement of atoms is due the expansion in freezing. Ice contracts and
expands by cold and heat the same as any other solid. The attraction of
crystallization begins, doubtless, to throw the atoms into their new and
crystalline arrangement at the temperature of thirty-nine and a half
degrees.

"We must remember that the heat which is set free in the condensation of
vapor and in the freezing of water is absorbed in the formation of vapor
and the melting of water. As much heat is taken from summer as is
conferred upon winter. The summer is cooled as much as winter is warmed.
The formation of vapor is a cooling process. Water is prevented from
rising above the boiling point by the formation of vapor. Perspiration
cools us by the evaporation to which it gives rise from the whole surface
of our bodies. And the higher the temperature, the more rapid the
evaporation, and the more vigorous the cooling process.

"We might look at other appliances for transferring heat from summer to
winter, but they belong in principle to another department. We have now
looked at some of the means for transferring heat in time. The heat is
treasured up at the heated noonday, to be brought out for use during the
cool hours of night; it is garnered from the excessive heats of summer to
supply the deficiencies of winter. It is laid up in store to-day to be
expended at any future time when needed. The transfer is a transfer not in
space, but in time. We must hereafter examine those arrangements by which
heat is transported through space. Some of these arrangements exert an
influence upon day and night and upon summer and winter, and thus throw
further light upon the subjects already discussed. Already more than once
topics have been suggested and their full consideration put off till some
more fitting time. In our next lesson we must begin the examination of
these new principles. We have before spoken of the vicissitudes of days
and seasons and years. We shall now have to do with the vicissitudes of
zones and lands and seas, of deserts and mountain ranges. The elements
become vaster, the stage is broader, and the movements more sublime.

"I am glad that you are so well interested in these great and beautiful
works of God's wisdom and power, but I hope that you do not forget that
the crucified Christ is pre-eminently the power of God and the wisdom of
God. These natural works are but the husk of which salvation from sin by
Christ is the kernel. These outward things are wonderful and beautiful for
the setting, but the gem, the royal precious stone, the Koh-i-noor, the
'mountain of light,' for which the setting was made, is the true knowledge
of the true God and of his Son Jesus Christ. During the past few weeks you
have heard others asking, 'What shall we do to be saved?' I should be
greatly guilty if I allowed you to think earth, air, and sea, with all
their silent and solemn movements, more important than our spiritual
attitude toward God the Father and Christ the Saviour. Are you, Samuel, in
your interest in studying Nature, forgetting Christ and the souls of men?"

"I hope not, and I think not. During the three years since my baptism I
have never felt so much my obligation to Christ as now. I never felt
before so deep a desire that my friends should repent and believe in
Jesus. I think the love of Christ constrains me. I have not felt before
that my work was very important; I have been expecting to work more
earnestly by and by; but lately I have felt that Christ gives me something
to do now for which he holds me responsible."

"What have you tried to do for Christ?"

"I have been praying for some of my young friends, and especially for
Ansel and Peter. And then I felt that I must talk with them as well as
pray for them."

"And can you, my young friends, be careless about your own salvation while
Samuel is so anxious for you? Are you contented to live 'having no hope
and without God in the world'? Is your happiness here and hereafter more
important to Samuel than to yourselves?"

"We are interested," said Ansel. "We have been talking together about
being Christians, but we don't know what to do."

"They said," broke in Samuel, "that they wished I would ask you to preach
a sermon and tell them what they must do to be saved. They wished to go on
with these lessons, but they thought that perhaps you would be willing to
preach a sermon just upon that subject."

"You know that I often speak of that subject, and when persons have come
to the inquiry-meeting I have told them what they must do. But I know that
there must needs be 'line upon line.' If Ansel and Peter wish it, I will
devote a sermon to the subject, and make it as plain as I can. Hardly
anything gives me more pleasure than to explain the way of salvation when
I know that my hearers are interested."

"We do wish to have you preach upon that subject, and I am sure that you
will have a great many interested hearers besides Ansel and myself."

"But, Samuel, did you not pray for Mr. Hume also, and talk with him?"

"I prayed for him, but I was afraid to speak with him. I have tried to
pray for him a double portion because I could not speak with him."

Tears gathered in Mr. Hume's eyes; the thought came to him that his
unbelief had raised a barrier between himself and both God and his people.
This pious young man was afraid to come to him lest he should meet the
scornful arguments and cold derision of a proud unbeliever. He felt
humbled--he, a subtle, well-read unbeliever, and Samuel a pious lad
yearning for the salvation of his soul, but daring only to pray in secret
for him.

"Have not you, Mr. Hume, been treating Christ and the Holy Spirit as
Samuel feared that you would treat him?"

"Perhaps so," he answered. "I am sorry that Samuel did not come to me
freely. I think he need not be afraid of me now. I also hope you will
preach the sermon which Ansel and Peter wish to hear."

Mr. Wilton assured them that he would do as they wished unless the Spirit
clearly drew him to some other subject. "I always look," he said, "to the
Holy Spirit for direction in my preaching. 'When he, the Spirit of truth,
is come,' said Jesus, 'he will lead you into all truth.' This was
fulfilled pre-eminently, I suppose, in the inspired men who laid the
foundation of the Church, but the Spirit still dwells in believers and
leads those who love and follow Christ. The preacher of the gospel can do
nothing without the power of the Spirit of God."

And I, kind reader, will give you the outline of the sermon if the Spirit
bids him preach it.



CHAPTER XI.

AN EFFECTIVE SERMON.


Mr. Wilton preached the sermon spoken of at the close of the last chapter
the next Lord's Day morning. The more he thought upon the matter and
inquired the mind of the Spirit, the more he felt that for a purpose the
Spirit was calling him to unfold again the authority of God and the
conditions of salvation. He gave notice of his subject, and invited all
good men to pray that he might be able, like a good and wise steward of
the mysteries of grace, to bring forth out of the treasure-house things
new and old, and that the word might prove as a nail fastened in a sure
place by the Master of assemblies. Much prayer was offered, and the people
came together in a spirit of unwonted solemnity and earnestness.

Mr. Wilton prayed to the glorified Redeemer for his blessing: "O thou
exalted Christ, we assemble in thy name and by thine authority. Thou hast
bidden us not forsake the assembling of ourselves together for thy worship
and the preaching of thy gospel. By thy grace we enjoy another of these
sacred days. By thy death thou didst purchase for thy people eternal
redemption. Thou hast wrought out for them a great and glorious salvation.
For thy great love wherewith thou hast loved us thou didst empty thyself
of divine glories, and madest thyself a servant among servants, and didst
suffer in the garden, and die upon the cross, and enter the grave. Now
thou art exalted at the right hand of the Father, a Prince and a Saviour,
to give repentance and remission of sins. O thou that judgest men, thy
justice is great and glorious as thy mercies. Years ago we tested thy
love, years ago we felt the shadow of thy wrath; our guilt made us afraid
and we cried unto thee, and thou forgavest our sins, and didst shed abroad
thy peace in our hearts. In these recent days thou hast brought other
sinners to feel their guilt. They have seen thee upon the cross, and have
been smitten with anguish, and have repented, and thou hast received
them. Others are bowed down; they mourn; they feel themselves poor and
needy; they confess thy justice; they feel the need of thy salvation; they
walk in darkness; they grope and find no light; they look unto thee from a
distance; but they do not come to thee, they do not follow thee. Wilt thou
not draw them to thyself? Wilt thou not bow their pride of heart and turn
their wills and make their hearts tender, gentle, and believing? Wilt thou
not smite the rock, and cause the waters of penitent grief to flow? Lay
thy cross, O Jesus, upon their shoulders and upon their hearts, that they
may bear it after thee and share thy glory. Open thou their eyes that they
may see eternal destinies and look upon thy divine glories, thy beauty,
and thy tenderness. Let them follow thee and trust in thee, strengthened
and comforted by thy rod and thy staff. O Christ, for thine eternal love
with which thou hast loved us, reach down thine arm mighty to save and
lift us up. Lord, save or we perish. And speak thou by thy servant to-day,
and cause all that hear to recognize the message not as his, but as
thine."

He read as his text Acts xvi. 30: "Sirs, what must I do to be saved?"

He briefly recited the arrest, imprisonment, and release of Paul and
Silas. "The salvation for which the jailer cried out was not deliverance
from the dangers of the earthquake, nor from the displeasure of the Roman
governor. This was the bitter cry of a soul sinking under a load of guilt
and trembling at the thought of God's impending wrath. Some of you can
appreciate his feelings and his fears. Your sins against God and Christ
and the Holy Spirit have risen up before you; they stare you in the face;
they condemn you. You feel your guilt--not a light and trifling fault, but
guilt deep and dark, such as creatures made in the image of God incur by
rebellion against the blessed and holy Creator. The Holy Spirit has
recited the divine law in your ears. Your consciences have heard that
voice and echoed its condemnation. You desire to escape that divine
displeasure; you desire to have the fires of guilt that burn in your
consciences quenched. You cry out, 'Men and brethren, what shall we do?'
The answer must be drawn from many parts of the Holy Scriptures.

"Understand, in the first place, that you are not to be saved by searching
out some plan of salvation for yourselves. Ask for the old paths. 'He that
entereth not by the door, but climbeth up some other way, the same is a
thief and a robber.' 'Other foundation can no man lay than that is laid.'
'There is but one name given under heaven among men by which we must be
saved.'

"Understand also that it is useless to attempt to save yourselves by
making yourselves righteous. You have tried, I doubt not, to make
yourselves better. Perhaps you have resolved that you would not come to
Christ till you can present yourselves in some degree worthy of his care.
Have you succeeded in getting rid of your sins? Can you blot out your past
sins? Can you erase the record which stands written in the book of
remembrance on high? The law of God written in this Bible condemns you;
God condemns you; you are condemned already for not believing in the name
of God's only begotten Son, the Lord Jesus from heaven. Can you change
that condemnation by your feeble, fickle resolutions to reform? 'Can the
Ethiopian change his skin or the leopard his spots? then may ye also do
good that are accustomed to do evil.'

"Be assured also that it does not belong to you to change your own hearts.
'Ye must be born again;' 'except a man be born again he cannot see the
kingdom of God.' But that second birth comes not of blood, nor of the will
of the flesh, nor of the will of man, but of God. 'Ye must be born again,
but ye must be born of the Spirit.' Notice that the word _saved_ is in the
passive voice. Sinners do not save themselves; they must be saved by
another; they must be saved by one able to save, by one almighty to save,
from the wrath of God and from sin, by one able to do for those who trust
in him all that they need to have done in order to make their salvation
complete and glorious. Christ is able to do this. The crucified and risen
Christ is exalted a Prince and Saviour, to give repentance and remission
of sins. The word of God says, 'To give,' and he rejoices to give.

"On one point we must pause and dwell with special clearness. Every
anxious sinner must not only feel his guilty and lost condition, but he
should also thoroughly understand what he means when he asks what he must
do to be saved. He should see to it that he wants that salvation which
Jesus gives.

"In the Scriptures the sinner who would be saved is called upon to return
to God. He has gone astray. He must retrace his steps. What is meant by
this? I mean that man's sin consisted at first and consists to-day in
saying, 'I will,' and 'I will not,' in opposition to the will and command
of God. God said, 'Thou shalt not;' man said, 'I will.' God says, 'Thou
shalt;' sinners say, 'I will not.' If a sinner is to be saved from sin,
this opposition must cease. When God says, 'Thou shalt not,' the sinner
must reply, 'I will not,' and when God says, 'Thou shalt,' the sinner must
answer, 'I will.' The sinner's 'will' and 'will not' must agree with God's
'shall' and 'shall not.' In place of your self-will you must put God's
will; that is, repentance, a turning about, a returning to God. But
remember, salvation, if it be real and thorough, is not submission for an
hour, a day, or a year, but submission for ever and ever. It is submission
without condition and without limits.

"The sinner says, 'This is a hard saying,' this utter and boundless denial
of self-will and selfishness. But is it hard that the creature should
yield to the Creator, that ignorance should yield to wisdom, that
selfishness should yield to love, that sin should yield to holiness, that
poor, lost, wretched, fallen man should yield to the eternal and
ever-blessed God? It is only by yielding that his will is brought into
sweet harmony with the will of God, and that he can be a sharer of the
divine blessedness.

"Your views on this point should be clear and distinct. If you wish only
to be saved from the penalty of your sins, you do not desire the salvation
which Jesus gives. He saves his people, not in their sins, but from their
sins. If, however, you really wish for his full and glorious salvation,
you will desire that your will may be wholly subdued to the will of God.
You will be found ready to unite in the memorable prayer of the Lord
Jesus, 'Not my will but thine be done.' Salvation implies the giving up of
self-will and a reverent submission to the will of God.

"Other sinful passions oppose the grace of God, but chiefly as helpers and
supporters of self-will. Pride and vanity strengthen self-will. Turbulent
fleshly lusts urge on and back up self-will. Fear of man, fear of danger,
and unbelief are but props of self-will. When 'my Lord Will-be-will'
submits, the town of Mansoul returns to her rightful allegiance.

"The question at issue between God and the sinner, the question of
self-will or submission, is often contested around the performance of some
single definite duty. The Holy Spirit often presents to the convicted
sinner's conscience some single duty and presses its performance. That
duty is a test of the feelings and desires of the sinner's heart. So the
Spirit understands it, so the sinner often understands it. As, in the
garden of Eden, God gave to Adam a test command, so does he now press upon
the conscience of convicted sinners test duties to show them what they
are. That which is required may be important, exceedingly important, in
and of itself, or it may be in itself of very little consequence, but in
every case the duty is all-important and its performance absolutely
essential, because the Spirit has laid it upon the sinner's conscience. It
will show whether he wishes for salvation from sin or not.

"I used to hear a Christian relate an experience like this. While the
Spirit of God was striving with him and conviction of sin was heavy upon
him, he felt a clear impression that he ought to go to his barn, and there
at one certain place upon the hay-mow kneel and pray. His self-will rose
in rebellion, chiefly, it would seem, because it was laid upon his
conscience as a duty. But his distress grew upon him. He went to his barn
and stood at another place and tried to pray, but no light or peace came;
his sense of his sins grew heavier. How could it be otherwise? He went to
the spot where he thought that he ought to go, and stood and prayed. Still
no peace came, but increasing sense of sin. At length he thought, 'Why
should I not? Why not give up my own will? Why not pray that God's will
may be done?' He yielded, he kneeled at the place where he had thought he
ought to kneel, and there he first felt peace before God. This was a
singular experience. Perhaps a man more intelligent and better taught in
the Sacred Scriptures would never have such a thing pressed upon his
conscience. But the battle of self-will is commonly fought around some
single definite duty. That duty may be a confession of wrong done to a
neighbor, or conversation with an impenitent associate, or a public
confession of sin before the great congregation. Whatever it may be, it
shows the sinner his heart and leads him to decide to follow his own will
just as he had always been accustomed to do, or it will lead him to pray
earnestly that he may be enabled in everything to bow his will to the will
of God. He will want the full salvation which Jesus in his grace brings
men--salvation from the penalty of sin and deliverance from its power.

"I draw no bow at a venture and speak not doubtfully when I say some of
you are standing face to face with duties pressed upon you by the Holy
Spirit. Your self-will, supported by pride, and fear of man, and unbelief,
and Satanic temptation, refuses to yield. The yoke of Christ seems to you
like bondage. The cross is supremely heavy. You draw back from it, and
refuse to bear it. I cannot take away the cross which the Spirit bids you
bear. I dare not do it; I will not do it. As the messenger of Christ, I
repeat the voice of the Spirit and lay the duty, whatsoever it may be,
upon your consciences. Do you really and honestly wish to be saved from
sin? Then you will yield to the Spirit's kind and gracious movings; you
will yield humbly but heartily. If, however, you want something else than
the salvation which Jesus gives, what can you expect but perplexity,
difficulty, darkness? I beseech of you, deal truly and faithfully with
yourselves on this point.

"To those who wish really to be saved I have good news to proclaim. There
is a Saviour such as you need. Trust in Jesus as your Saviour. Place the
whole work of your salvation in his gracious hands. Christ saves sinners
just such as you are. The faith which you are but to exercise is nothing
else than your confidence, by which you entrust yourselves to him. Faith
has no saving virtue in itself, but it is the hand by which the sinner
takes hold of Christ. With this duty few of you will have any great
difficulty. When once you wish to be saved from sin and are ready to
submit to the will of Christ, you will have no reluctance to take him for
your Saviour. You believe that Christ is a divine Saviour. If saved at
all, you expect to be saved by him who died on Calvary. Hardly for the
world would you resign your opportunity of coming to Christ and receiving
his grace. You believe that Jesus is the Christ, the Son of the living
God, the great sacrifice for sin. It remains that you should gladly accept
what he offers and follow him as loving, trusting disciples.

"Follow the Spirit, and you will be led to Jesus and will come speedily to
the joy of salvation; resist the Spirit, and you grope in boundless
darkness and fall upon the dark mountains.

"In the Holy Scriptures the question of the text is asked and answered
many times. Hardly any two answers are alike. Are there different
conditions and different duties required of different men? By no means.
But the Holy Spirit adapted the answer to the different spiritual states
of the various inquirers. The answer is made to each questioner's heart. A
self-righteous young man came to Jesus asking, 'Good Master, what good
thing shall I do that I may inherit everlasting life?' Jesus answered,
'Keep the commandments: thou shalt do no murder; thou shalt not commit
adultery; thou shalt not steal; thou shalt not bear false witness; honor
thy father and thy mother; and thou shalt love thy neighbor as thyself.'
The young man answered, 'All these have I kept from my youth up; what lack
I yet?' Jesus said, 'If thou wilt be perfect, go sell that thou hast, and
give to the poor, and thou shalt have treasure in heaven, and come,
follow me.' The young man went away sorrowful. Jesus knew his
self-righteousness, and gave him answers which opened that young man's
eyes to see himself. He gave him a test command, and the young man's
revulsion from that duty showed that, notwithstanding his self-confident
claim to righteousness, his riches filled all his heart. If your hearts
are filled with the love of the world, you must put your possessions out
of your hearts and follow Jesus.

"Nicodemus also came making the same inquiry. He must have asked something
like this, for Jesus answered such a question. 'Ye must be born again; ye
must be born of the Spirit,' said Jesus. Nicodemus was looking for a legal
salvation by outward formal services, but Christ gave him to understand
that salvation involves a great spiritual renovation wrought by the Holy
Spirit, by which men old in sin become new creatures and enter the kingdom
of God as little children. He taught him thus that salvation was only from
God. If any of you are looking for a cloak of self-righteous religious
duties which you can put on, be assured that true religion springs from a
work of God wrought in the heart. You must be born again by the power of
the Holy Spirit. You must become new creatures in Christ Jesus.

"On the day of Pentecost the great company of men 'out of every country
under the whole heaven,' while listening to Peter's pungent address, cried
out, 'Men and brethren, what shall we do?' 'Repent and be baptized, every
one of you, in the name of the Lord Jesus, for the remission of sins,'
answered Peter. Here were men who had a hand in crucifying Christ, or if
they had no active share in that deed of darkness, they had consented to
his death; they were partakers of the crime; very likely they had cried,
'Crucify him, crucify him.' They saw their sin, and were pricked in the
heart. Well might they repent of their rejection and crucifixion of their
promised Saviour, the Son of God, from heaven. Others were devout men who
had come to Jerusalem to worship. Like Simeon they may have waited long
for the consolation of Israel. How easy for them to enroll themselves
among the followers of Christ! All alike are commanded after repentance to
put on Christ by baptism. That burial with Christ was the symbol of their
dying and living again--of their dying unto sin and living again unto God.
The same duties are enjoined upon you. Repent of your long rejection of
the grace of God and his Son Jesus Christ, and before God and men devote
yourselves to his service by a public confession of Christ in baptism.

"The jailer of Philippi was taken in the midst of his sins. He was holding
the servants of Christ in his dungeon. He knew for what offence they had
been seized, and he made himself a partner in the crime of persecuting
them by the zest with which he thrust them into the inner prison and made
their feet fast in the stocks. His conscience was ill at ease. Then came
the earthquake's shock, and he felt as if called to stand face to face
with his Judge. His soul was pierced through and through with a sense of
guilt. 'What must I do to be saved?' he cried in the bitterness of his
conviction. 'Believe on the Lord Jesus Christ, and thou shalt be saved,'
answered Paul. This is the answer to all of you who are well convicted of
sin and have given up all self-righteous hopes. Christ saves you. Look to
Christ, ask Christ; whosoever comes to him he will in no wise cast out.
Will you not come to him? Will you not trust his promises and commit
yourselves to his hands to be saved? He waits to bless you. He delights
to be gracious. To save sinners he lived among men, and died and has
ascended. His hands are full of gifts. He comes to you, and stands and
knocks at the door of your hearts. Will you bolt the door? There is joy in
heaven over repenting sinners. This alone of all earthly transactions
carries joy to Christ and the angels. Accept of Christ, and earth and
heaven will throb with a common joy."

These words were listened to with most earnest attention, for at that time
Christ and heaven were realities in the minds of men, and salvation was a
living issue. Mr. Wilton spoke as an earnest man, without cant or
circumlocution, pressing upon men of thought and conscience the great
concerns of eternity. The full result of this discourse will be known only
when the opening of the books at the last day shall reveal it, but the
beginning of the result was seen in the evening prayer-meeting. When the
invitation was given for anxious persons to make known their feelings,
both Ansel and Peter arose, and confessing in few words that the Spirit of
God had been striving with them, and that they had been resisting the
Spirit, said that now they were determined to resist no more, and asked
Christians to pray for them that they might be able to submit fully to the
Lord Jesus and trust entirely in him. Then there was a pause. Mr. Wilton
was just on the point of rising to close the meeting when Mr. Hume rose to
his feet. After a sudden start of surprise, a deep hush passed over the
congregation, and in the midst of deepest silence Mr. Hume said:

"I have been more than merely an impenitent man: I have been an
unbeliever; I have been an infidel. I have not only tried to disbelieve
the Holy Scripture, but I have actually disbelieved. I have thought myself
wiser than the word of God. I do not mean that I have enjoyed peace, that
my conscience has been at rest, and that I have been happy in my unbelief.
Three months ago I began to grow more than usually discontented with
myself. Questions which I counted settled and put to rest for ever came
back to trouble me. A hundred times a day the questions came, What if
there be a God who holds me responsible? What if there be a future life
and a judgment day? What if Christ be the Son of God? Why such questions
should haunt me day and night I could not tell. I have learned to believe
that the Spirit of God was speaking to me. This restlessness brought me to
the church for half a day. If my object was to gain rest in unbelief, I
could not have done worse. My old arguments were unavailing to break the
force of the truths preached. The questions which had been sounding in my
ears and echoing in my heart began to change to solemn affirmations:
'There is a God;' 'There is a day of judgment;' 'Appointed unto man once
to die, and after that the judgment;' 'Christ is risen.' Texts of
Scripture learned in my boyhood and forgotten long years ago came back
fresh to my memory. But I will not stop to rehearse to you all my
struggles of mind for two months past. For a few weeks you have seen me
here. I determined that I would try to find Christ if he manifests himself
to men in these latter days. For two weeks I have tried to pray, but I
have found no satisfaction. Christ has not manifested himself. My darkness
has grown deeper and deeper. I have sometimes almost determined to abandon
all thought of Christ and throw myself back again upon my former
unbelief. But I could not lay down the subject.

"Since I began to try to pray I have felt, faintly at first, like the
whisper of a suggestion, but becoming clearer and stronger, like a voice
from heaven, that I must in this congregation confess my former state and
the feelings which I have had. It seemed to me that I could not do this.
It seemed easier to die than to stand up here and confess that my belief,
which I had pressed upon others and had boasted of as better than the
gospel, had given me no peace. To-day I have been made to understand that
the Spirit of God has set me face to face with this confession. I have
seen what it means to be saved--that my self-will must die or I must bid
adieu to Christ and hope. I cannot live and die hopeless. I cannot rest my
head upon unbelief. I confess to you that all my thoughts have been wrong.
My beliefs and my unbelief have done me no good. My whole life has been
enmity and opposition to the Holy Spirit. I will try to oppose the Spirit
no more. I know not what the Spirit may lay upon me, I know not how soon I
may break my resolution, but I now feel that I want to be saved from sin,
and cannot do otherwise than follow the Spirit though I dwell in darkness
for ever. If Christ reject me I cannot complain, but if you think there is
hope for one who has so despised the grace of God, I entreat you to pray
for me."

It is needless to say that from scores of family altars and closets
supplications went up to God that night for the salvation of Mr. Hume and
Ansel and Peter, and men prayed especially that Mr. Hume, who for years
had been such a tower of strength to the ungodly and the dread of
Christians, might be saved for the glory of Christ and the confounding of
unbelievers. Those prayers were heard. When the report of that meeting and
that confession went out through the community, unbelievers were silent.
It was as if the God of battles had emptied his quiver into the hearts of
his enemies.



CHAPTER XII.

TRANSFER OF HEAT IN SPACE.


"We now turn our attention," said Mr. Wilton, "to a new theme. In the
vicissitudes of day and night and of summer and winter heat is transferred
_in time_. We now are to look at the arrangements by which heat is
transferred _in space_. But since the transfer of heat in space requires
more or less of time, the means employed are such as suffice to accomplish
both objects. Heat is treasured up and carried away to distant regions,
and delivered up for use as occasion demands.

"In a previous lesson the inclination of the earth's axis was spoken of.
By this means the northern hemisphere of the earth is turned somewhat
toward the sun during one half of the year, and receives a correspondingly
larger portion of heat, while during the other half of the year the
southern hemisphere is turned toward the sun and is warmed. This
inclination of the earth's axis to the plane of its orbit gives us the
change of seasons.

"The change of seasons is manifestly designed for the welfare of man.
Along with the genial warmth of summer, fruits and grains and the comforts
of life are carried far toward the poles, into regions which otherwise
would be desolate with perpetual frost. But these extremes need to be
softened; otherwise, the violence of the changes would prove destructive
rather than beneficent. The severity of these annual changes of
temperature is ameliorated by some of the grandest movements and
arrangements upon our globe. These arrangements we have in a very
imperfect way already examined.

"But there are other inequalities of temperature besides those of day and
night, summer and winter. Passing from the equator toward the poles, every
degree of the earth's surface passed over causes the sun to sink one
degree from the zenith toward the horizon, and gives a corresponding lower
temperature, till within the polar circles for a part of the year the sun
is entirely hidden and winter reigns without a rival. The temperature of
the sea differs from the temperature of the land; the sun comes nearer to
one hemisphere than the other, and remains longer north of the equator
than south. These and many other differences upon the earth give to
different parts of the world every possible variety of temperature and
climate. These differences of temperature upon sea and land, from zone to
zone and from hemisphere to hemisphere, are equalized or ameliorated by
many agencies, but chiefly by a transfer of heat in space, a transfer of
heat from place to place.

"I do not need to tell you that while we in the northern hemisphere are
enjoying the warmth of summer the southern hemisphere is enduring the
severities of winter, and in turn, when winter comes to us, summer smiles
upon the nations that live south of the equator. You also remember that
the orbit of the earth is not an exact circle, but an ellipse, that is,
what is sometimes called in common language a long circle. For this reason
the earth is three millions of miles nearer the sun in one part of its
orbit than when in another part. Can you tell us, Peter, at what season of
year the earth is nearer the sun?"

"In midwinter, or about the first of January. I have always remembered it
because it seemed so strange to me, when I learned it, that the sun should
be nearest the earth at the coldest season of the year."

"Yes, one is reminded by it of the humorous argument that the sun must
emit cold instead of heat, because when we are at the point of the earth's
orbit which is nearest the sun it is winter, and the higher one ascends
upon mountains toward the sun, the colder he finds it. But this nearness
of the sun while south of the equator would naturally give the southern
hemisphere a warmer summer than the northern. For this there is a
beautiful compensation. The earth passes through her orbit more rapidly
when nearer the sun, and that half of her orbit is also smaller, so that,
as the result of this, the sun remains north of the equator about eight
days longer than in the southern hemisphere. The sun is nearer while in
the southern hemisphere, but the summer is shorter. That which the
southern hemisphere gains in distance it loses in time, and that which the
northern loses in distance it gains in time.

"The nearness of the sun while south of the equator, the shortness of the
summer, and the corresponding distance of the sun and length of the
winter would tend to give the southern hemisphere great extremes of heat
and cold, a short and hot summer and a long and cold winter. For this also
there is a most interesting compensation in the comparative amount of land
and water north and south of the equator. Much more than one-half of the
dry land lies in the northern hemisphere. This would tend to give the
northern hemisphere extremes of heat and cold. South of the equator there
is comparatively little land and much water, which tends to give the
southern hemisphere evenness of temperature. The inequalities of the
earth's orbit and the earth's motion in its orbit we find counterbalanced
by the arrangement of land and water upon the earth's surface.

"In connection with this we may notice still another compensation in the
elevation of the lands by which the burning heat of the torrid zone and
the rigors of the colder zones are more or less diminished. The greater
the elevation of any region of country, the cooler must be its climate.
Physical geographers like Baron von Humboldt and Guyot have made
calculations which show that those grand divisions of the earth which lie
in the hot regions of the earth are most elevated above the sea level.
South America lies higher than North America, Asia is more elevated than
Europe, and Africa is more elevated than Asia. The continents rise as they
approach the equator and sink toward the sea level as they come nearer the
poles. As these colder lands approach the water level their valleys sink
beneath the sea, their coast lines become deeply indented with bays and
gulfs, and lakes abound. Thus the warmer waters of the sea are
interspersed among the cooler lands, and the temperature of the lands is
raised. The very elevation of the continents and the configuration of the
lands have a providential relation to the temperature and climate of the
world. We cannot suppose that arrangements like these, so aptly fitted to
the needs of man, came by chance. In the unmeasured ages past, while this
earth was in preparation for man, God had the beneficent _end_ in view;
nay, in the very beginning, the whole plan and its beautiful completion
was had clearly in mind. Millions of ages ago the great Creator tenderly
considered the comfort and well-being of the human race, the latest born
of his creatures, in these last ages.

"As a general statement, the torrid zone receives an excess of heat, while
the frigid zones receive too little, and the temperate zones, lying
between, receive, at different times and places, sometimes too little and
sometimes too much. The providential arrangements for equalizing
temperature are, then, chiefly arrangements for conveying heat from the
overheated tropical regions and scattering it over the temperate and polar
regions. First among these means we will notice the _trade-winds_, or, as
for the sake of brevity they are often called, 'the trades.' Will you tell
us, Samuel, how winds are caused?"

"The air is heated at some place and expands; it becomes lighter and
rises, while the colder air around rushes in to fill its place."

"You use the words which are commonly employed in explaining the origin of
winds, and very likely your idea is right, but the language needs a little
correction. The warm air does not rise of its own accord, so to speak, but
is pressed upward. The warm air is expanded; it presses outward and
upward; the same weight of warm air occupies more space than cold air;
the warm air rises and overtops the surrounding air, and then flows off in
order to reach the common level. The column of warm air is lighter than
the cooler air, and cannot balance it; consequently, the cold air sinks
down, pressing the warm air upward. In this manner an ascending current of
warm air is formed, and also currents of cold air flowing from every
direction toward the warm centre. These currents continue until the
temperature of the air is equalized.

"The atmosphere is commonly believed to be forty-five or fifty miles in
height, though some men have estimated its height as very much less than
this, while others believe it to be six or seven hundred miles in height.
Are we to suppose that the column of heated air reaches to the top of the
atmosphere?"

"I think not," answered Mr. Hume. "The rarefaction of the lower part of
the column renders the whole column lighter than the air around, and the
warm air, as we know by the movements of the clouds, after rising a little
way, spreads off in every direction, forming upper currents corresponding
to the currents below, but moving in the opposite direction."

"Only a few days ago," remarked Peter, "I saw in the same part of the sky
clouds moving in exactly opposite directions, and others which seemed to
be standing still. I knew how one layer of clouds might be moving north
and another layer moving south, but I did not understand why some should
be standing still."

"Do you imagine, Peter, that the upper and lower currents of air, moving
in opposite directions, come sharply together, the one sliding against the
other?"

"I think not," said Peter.

"Supposing, then, as is certainly true, that a stratum of still air lies
between the upper and lower winds, does not that explain how certain
clouds might be standing still while the others were moving?"

"I might have thought of that myself."

"But how does this carry heat from the warmer region to the colder regions
around?" asked Ansel. "I see how the colder air coming in would cool the
warm region, and how the warm ascending air would carry away the excess of
heat, but how do the cooler regions get the advantage of this heat?"

"That is just what I was on the point of explaining. Do you remember what
was said about the production of cold by expansion and of heat by
compression?"

"I remember that if air be rarefied by removing pressure from it, its
temperature falls: I think you said that a part of its sensible heat
becomes latent; and if air be compressed, its temperature rises. I have
seen experiments with the air pump and condenser to prove this."

"That principle explains the transfer of heat by winds. If the heated air
rose to the upper regions, and there radiated its heat, nothing would be
gained; the heat would be simply radiated into space. But as the warm air
rises pressure is more and more removed from it; it expands; its sensible
heat becomes latent and is thus kept from radiation; its temperature
falls, but not from loss of heat. This rarefied air forms the upper
current flowing away from the heated centre. In due time this air must
come to the surface of the earth again. Whenever this takes place the air
is brought again under pressure; it is compressed, and its latent heat
becomes again sensible. Heat is thus transferred from the warmer region to
the colder in a latent condition, so that it cannot be lost. We must now
apply this to the trade-winds. What are the trade-winds, Mr. Hume?"

"They are regular winds blowing from a little north and south of the
tropics of Cancer and Capricorn south-west and north-west toward the
equator."

"These winds are called _trade-winds_," continued Mr. Wilton, "on account
of their great advantage to trade or commerce. The regular and steady
sweep of these winds bears the merchantmen rapidly and safely on their
way. The formation of 'the trades' is easily explained. By the intense
heat of the sun under the equator the air is greatly expanded and
rarefied; the heated air rises along the whole line of the equator; from
both sides the cooler air presses in, is heated, and rises; thus steady
winds are formed from the tropics, or a little beyond the tropics, toward
the equator. If the earth had no rotation upon its axis, these winds would
blow directly toward the equator, exactly south and north. The rotation of
the earth gives the trade-winds their oblique, south-west and north-west
direction. Suppose that a single particle of air at the tropic of Cancer
starts upon its journey toward the equator. At its starting it has the
same motion eastward as the surface of the earth at that place, that is,
about nine hundred and fifty miles per hour. But as it moves on southward
the degrees of longitude become longer and the motion of the earth's
surface becomes more rapid, till at the equator its motion is one thousand
and forty miles per hour. But the particle of air we are watching is not
fastened to the earth's surface, and as the earth moves more rapidly the
nearer we come to the equator, the particle of air falls behind, that is,
the air moves southward and eastward, but the earth moves eastward more
rapidly than the air, so that the air falls behind and seems to be moving
westward. The result is that the air upon the earth's surface moves
south-west. That which takes place with a single particle takes place with
the whole body of the air, and that which takes place north of the equator
takes place south of it also, producing north-west winds. On reaching the
equator the winds from the north and the south meet and stop, forming the
equatorial calms, and mingling together, they rise into the higher
regions. In rising, the air bears away heat from the torrid zone, and this
heat, rendered latent by the expansion of the air, is carried north and
south by the upper currents as far as the limits of 'the trades.' In due
time these upper currents descend and their latent becomes sensible heat,
and is used in raising the temperature. Mr. Hume, can you suggest any
method by which we can estimate the amount of heat which is carried north
and south by the return trades?"

"I know of no method, except to estimate the amount of heat necessary to
raise that flood of air which pours in from the temperate zones to the
equatorial heat. That immense amount of heat must, nearly all of it, be
carried away to the temperate regions."

"This is the general explanation of the trade-winds. You must understand,
however, that, in certain regions and under certain conditions, the trades
are liable to interruption or change of direction. Desert regions within
or near the tropics give rise to local winds which overpower the trades.
In Southern Asia, while the sun is north of the equator, the land becomes
so much hotter than the sea under the equator that the trade-wind is
overpowered and reversed, forming a wind which blows to the north-east
instead of the south-west. But this is only a beautiful flexure, so to
speak, of a general arrangement for the greater advantage of a particular
region. By this means the summer winds of Southern Asia come from the sea.
Northern winds would have been dry. Prevailing northern winds would have
made the whole of Southern Asia a desert; but the south-west monsoons come
from the Indian Ocean laden with vapor, and render Southern Asia a very
garden for fertility.

"The next great agency for equalizing temperature between the torrid and
temperature zones is the formation and condensation of vapor. This comes
in here, because it depends for its efficiency upon the agency of winds.
More than once this method of conveying heat from place to place has been
hinted at, but deferred till we came to the proper place to speak of
winds.

"The trade-winds, passing over from a colder to a warmer climate, are
constantly accumulating vapor. Under the equator the annual evaporation
from the surface of the ocean is set down at fifteen feet, or half an inch
daily. The formation of this vapor consumes heat which would boil more
than eighty feet of ice water. The vapor thus formed is borne upward by
the ascending current of heated air. On reaching the higher regions a
portion of it is condensed and forms a belt of clouds around the earth.
This belt of clouds along the equator is known as the 'cloud-ring.' This
cloud-ring shields the belt of calms from the burning rays of the sun and
sends down almost incessant rains. But does not that condensation which
forms the cloud-ring set free latent heat, and thus intensify the great
heat of the equator? Latent heat becomes sensible, but it is given out
into the ascending current of air, and serves only to give it another lift
till by expansion of the air it again becomes latent. The heat is simply
transferred from the vapor to the air. The vapor which remains uncondensed
is borne away on the wings of the return 'trades' to the south and to the
north, and in due time is condensed and returns to the earth as rain; the
heat which is given out by its condensation, wherever and whenever it is
condensed, is given over as latent heat to the keeping of the air, and is
passed back for use whenever the air descends to the earth.

"Vapor gathered from sea or land is everywhere exerting this equalizing
influence upon temperature. Does the temperature rise in any place? Vapor
is formed. Every moist body begins to give up its moisture, and the excess
of heat is employed in turning this water into vapor. This is the method
by which perspiration cools man or beast; whether it be insensible
perspiration from the invisible pores of the skin, or perspiration
standing in beady drops upon the face of the toiling laborer, vapor is
formed and heat is carried away. Have you not noticed on close, muggy days
when nothing dries, showing that very little vapor is forming, that
perspiration seems to have no cooling effect? It oozes from the skin, but
does not evaporate, and hence does not carry off the surplus heat. Animals
like dogs and oxen, that do not become wet with perspiration, do not bear
heat well; they soon pant and loll, attempting to get rid of the excessive
heat through the moist breath and open mouth.

"The sum-total of heat transferred by this agency is too great for
comprehension. Look at the Amazon rolling to the ocean a flood broad as an
arm of the sea. That great river is brought from the Atlantic Ocean on the
shoulders of the trade-wind. As the vapor is slowly lifted by the rise of
the land from the sea level to the summits of the Andes, it is condensed,
and falls as rain. Well is it for South America that the Andes were thrown
up on the western coast, for the winds west of the mountains are dry as a
pressed sponge, and the most of that narrow slope is barren and desolate.
South America would be a desert if the Andes ran along the eastern coast.
Look at the Mississippi, and the great rivers of Europe, and the matchless
rivers of Southern Asia. All the rivers of the world represent only the
_wastage_ of the rain which falls upon the land after supplying the wants
of the vegetable kingdom and keeping the lands moist. All this water is
lifted into the air by heat, and every movement of vapor is a movement of
heat. Every particle of vapor goes freighted with heat. Every cloud driven
across the sky represents the transfer of heat, and every transfer is in
the direction of equalization. Everywhere the tendency is to equilibrium.
Nature has no processes for transferring heat from colder to warmer
regions.

"We may form a conception of the amount of heat transferred by the agency
of vapor by estimating the amount of heat-force required to evaporate the
water which forms our rain-clouds and lift them into the upper regions.
According to a calculation of Mr. Allen, late of Providence, to evaporate
one-eighth of an inch of water daily from that belt of the surface of the
earth lying within the tropics, and raise it five thousand feet high,
requires 4,700,000,000 horse-power, or one hundred and thirty times the
effective force of the whole human race, reckoning it at 250,000,000
able-bodied men. But the actual evaporation from the sea within the
tropics is believed to be about half an inch daily--four times as great as
Mr. Allen's supposition.

"I see, however, that our time is nearly exhausted, and I wish before
closing to revert to that more important theme upon which I spoke this
forenoon. I do not know how the truths preached interested or affected
you, nor do I now wish to have you tell me. I wish only to say that, as
the sermon was preached at your request, I hope it proved applicable to
you, and that you will give the truths presented earnest attention.
Consider them well, and make your conclusions known this evening."

The conclusion which the evening made known, you, reader, have already
learned.



CHAPTER XIII.

OCEAN CURRENTS AND ICEBERGS.


A week has passed since Mr. Hume made his frank confession. He went home
no lighter of heart than before, yet he felt in some respects different,
for he had attempted to do what was right in the sight of God. But he did
not feel the joy of sins forgiven. He had not looked upon Christ as a
Saviour for himself. He felt that God had distinctly set life and death
before him. His doubts were gone; the spiritual world was a reality;
Christ stood at his right hand and Satan at his left; he stood where the
path of destiny divided, the one path leading up to heavenly seats with
Christ, the other leading down to darkness and despair. A voice seemed to
be whispering in his ears, "This is the last call." He went to his chamber
determined, if possible, to settle the question of life or death before
he left the place and before he slept. He took his Bible, and on his knees
turned and read the Psalms at random. But the cloud of darkness only
gathered deeper. The words of David's penitential Psalm caught his eye:
"Against thee, thee only, have I sinned, and done this evil in thy sight."
He felt that these words of David were true in his case also. All his long
impenitence and bold unbelief had been against God. By night and by day,
for many a long year, before the sleepless eye of God, he had lifted up
his hand, almost defying the holy One, yet the lightning of God had not
smitten him. He wondered as much at the long-suffering of God as at his
own dreadful daring of the divine wrath. He had been taught better things;
he was trained to know the Scriptures and to go reverently to the house of
God, but he had turned from Christ and hope. He read on: "Deliver me from
blood-guiltiness, O God, thou God of my salvation." He felt that this
belonged to himself more than to David. David had shed the blood of
natural life, but he had destroyed the souls of men. He had stood chief
among unbelievers. He had led young men into infidelity. He had seen them
drink in his unbelief like water, throw off all restraint, and rush
headlong to ruin. He had wrought a work of evil which he could never undo,
and for which he could make no atonement. What was a confession in
comparison with the ruin he had caused? What could his confession do for
the young men already, perhaps, among the lost through his influence?
Could his late repentance call them back to life and hope? Would God
forgive and raise to heavenly heights a man who had dragged others down to
hell? Would it be possible that Christ should fill his soul with
blessedness while his victims were drinking the wine of the wrath of God?
A deep horror seized him. The darkness of eternal death seemed to enfold
him. Must he, then, after having caught a glimpse of life and joy, be cut
off from hope and be driven from God for ever? This would be just, but he
felt that he could not endure it. "O thou great and holy God," he prayed,
"I will ascribe righteousness to thee though thy righteous wrath shall
sink me to hell; but, O thou merciful God, my soul cannot endure thy
justice. The foretaste of thy wrath fills me with the pangs of eternal
death. O God, have mercy upon me. O God, blot out my transgressions.
Create in me a clean heart, and renew a right spirit within me. O Christ,
whom I have despised, cast me not from thy presence. Help me to submit to
thee. Help me to follow thee. Spare me that I may undo something of that
which I have done against thy glory and the souls of men. O Jesus, I can
do nothing to save myself. O Lord, have mercy on me, the chief of
sinners."

He read the invitations and promises of Christ, and prayed again. Again he
read and again he prayed. Little by little the promises of Christ stirred
a feeble faith in his heart; he felt that there was still hope for him,
and with the determination to cast himself upon the sure mercies of Christ
and to devote himself to his service, he threw himself upon his bed, and
being wearied almost to exhaustion, soon fell asleep. When he awoke it was
broad daylight. He had slept a sweet, refreshing sleep. But he was
refreshed not merely in body. He woke to a new world. His heart was filled
with sweet thankfulness. "How beautiful," he said, "is God's world! I
never saw it so before, but the earth and sky seem clothed in glory. But
most wonderful of all is God's goodness to me. I have rebelled against him
all my life, yet he has loved me and sought for my salvation, and now the
sunlight of his love has broken through the thick clouds of my sin, and a
day of hope and joy has dawned upon my life. Christ has indeed revealed
himself. Blessed be his holy name for ever and ever! What shall I render
unto the Lord for all his benefits? I will take the cup of salvation and
call upon the name of the Lord. I will pay my vows now in presence of all
his people. I will teach transgressors thy ways, and sinners shall be
converted unto thee."

All this was known to the people, for during the week Mr. Hume had spoken
of it in private and in public. He had told it to Mr. Wilton, and they had
rejoiced together.

Ansel and Peter had also regularly presented themselves at every meeting
as anxious inquirers desiring the grace of God. Peter had also on his
knees said from the heart, "Here, Lord, I give myself away," and had
received the assurance that his sins were forgiven. The Spirit of God
witnessed with his spirit that he was born of God. He began at once to
use all his influence to bring his young friends to Jesus. The addition of
two such workers as Mr. Hume and Peter, each moving in his own circle of
acquaintances, gave a fresh impulse to the religious interest, which was
now becoming deep and pervasive. Especially had Mr. Hume's conversion, so
clear and positive, confounded those who had sat "in the seat of the
scornful," and many came in now for the first time to see for themselves
what it could be that had mastered their cold, clear-headed leader in
unbelief.

But Ansel still walked in darkness. He had talked with Mr. Wilton, but no
light had entered his mind. He said that he thought he had submitted in
all things to the will of God. He was becoming impatient that Christ had
not come to him as to others. This was their condition as they came
together upon the Lord's Day. They all understood each other, and had no
need now to ask questions or make explanations. Mr. Wilton believed that
the study of God's works would not interrupt the working of the Holy
Spirit, and therefore went on with his lesson as usual.

"We have already spoken of the transfer of heat from the torrid to the
temperate and frigid zones by the agency of winds and watery vapor. These
carry heat chiefly in a latent condition. But great movements of heat take
place in a sensible state. In this transfer of heat, also, water is the
great carrier. The winds and vapor go freighted with latent heat above,
and the waters and wind go freighted with sensible heat below. We will
first examine the operation of the ocean currents.

"Not only do rivers run through the lands and hasten to the sea, but in
the midst of the oceans rivers are flowing in comparison with which the
Mississippi, the Amazon, and the Yang-tse-kiang are rippling brooklets.
The earth is belted by these ocean streams traversing the seas. An ocean
current, called the Gulf Stream, issues from the Gulf of Mexico between
the Florida coast and the Bahama islands. It flows northward off the coast
of the United States, gradually increasing in breadth and spreading over
the Atlantic Ocean. It is deflected by the New England coast and the great
shoals off Newfoundland, called the Grand Banks, or else by another
current flowing southward from Baffin's Bay, and strikes across the North
Atlantic, bathing the shores of the British islands and reaching even to
Iceland.

"The general outline of the ocean currents is this: issuing from the South
Pacific, a current flowing eastward splits upon Cape Horn. The western
portion, called Humboldt's current, flows northward along the western
coast of South America, and is swallowed up and lost in the great
equatorial current of the Pacific. This is a broad current flowing
westward and covering the entire space between the tropics. Striking upon
the eastern shores of Asia, this equatorial current divides, one part
flowing northward along the coast of Asia, the other finding its way
through the many islands, sweeping across the Indian Ocean, and flowing
down the eastern shore of Africa on each side of Madagascar. Doubling the
Cape of Good Hope, the current continues in a north-westerly direction
across the Atlantic. Striking upon Cape St. Roque, this current again
divides; a part flows south and a part pours into the Caribbean Sea. From
the Caribbean Sea it issues as the Gulf Stream, of which I have already
spoken. This Gulf Stream impinges upon the western coast of Europe, and
pours partly into the North Sea and partly flows south off the western
coast of Africa, completing thus the circuit of the Atlantic. The currents
of the Indian and of the great Southern Oceans are as yet very imperfectly
understood. Of all the ocean streams the Gulf Stream is most famous and
best understood. I shall therefore use this as an illustration of the
agency of ocean currents in conveying heat and modifying climate.

"The waters of the Caribbean Sea are heated by the tropic sun to
eighty-eight degrees. From these heated waters the Gulf Stream issues
salter and warmer, and of a deeper blue, than the waters of the
surrounding sea. Its greatest velocity as it issues from the gulf is a
little more than three miles per hour. As it flows northward its velocity
diminishes, its breadth becomes greater, and its depth less. It covers
thus with its warm waters a broad belt of the Atlantic Ocean, and extends
its influence to the most northern part of Europe. You can judge of the
amount of heat which is removed from the tropics when I tell you that the
unmeasured flood of the Gulf Stream would swallow up three thousand rivers
like the Mississippi. This one ocean stream is many times greater than
all the rivers of the world. We feel the warmth of the Gulf Stream with
every wind that blows from the sea. To this the British isles owe their
mild, moist climate and perennial greenness, and by its influence a winter
in Iceland, upon the Arctic circle, is no more rigorous than a winter in
Montreal, twenty-one degrees nearer the equator. But what is the Gulf
Stream, though it be fifty fold greater than all the rivers of the world,
in comparison with the whole sum of the ocean streams? Upper currents and
under currents fill the sea. They meet the explorers of the sea
everywhere. The navigator drops his measuring line, and finds it swept
away and drawn out by unseen currents. All these movements of the waters
are in favor of the equalization of temperature. The cooler waters of the
frigid and temperate zones are mingled with the heated waters of the
tropics and exchanged for the equatorial waters. The transfer of heat
would not be greater if broad rivers of molten lava were flowing from the
equator to the poles.

"Another agency for the transfer of heat is the movement of ice, and
especially of icebergs."

"Will you not tell us," said Samuel, "how these ocean currents are
produced? I can understand how winds are formed, but I do not see that
these streams in the sea could be formed in the same way."

"I designed to speak of this, but for the moment it had slipped from my
mind: I am glad that you called my attention to it. I do not expect,
however, to give a full and satisfactory account of their origin. If I
should do this, I should succeed where every other man has failed. I shall
not attempt a full explanation. By some means or other, the waters of the
ocean are thrown out of equilibrium, and these currents are plainly an
effort to restore the balance or equilibrium of the waters. Many
influences and agencies conspire to disturb the equilibrium of the sea.
The attractions of the sun and moon are constantly counteracting the
attraction of the earth and lifting the waters, so to speak, above their
natural level. The tides produced by these attractions of the sun and moon
are the immediate cause of some of the minor local currents. The winds set
the waters in motion, tending to pile them up in one place and leave the
sea below its natural level at another. The effect of strong winds in
piling up the waters, even upon our great lakes, is very considerable. A
heavy east wind upon Lake Erie has been known to drive the waters toward
the western end of the lake so much as to leave Niagara River above the
falls almost dry. On the other hand, a heavy west wind drives the waters
eastward, and produces almost a flood in the river. The influence of
constant winds like the 'trades' acting upon an immense expanse of water
must be very much greater. Unequal evaporation tends to destroy the
balance of the waters. In the colder regions the evaporation is very
little, while within the tropics it amounts to about half an inch daily,
or fifteen feet per annum. The head of the Red Sea is two feet lower than
its mouth on account of evaporation. This unequal evaporation causes also
an unequal saltness, and consequently an unequal weight. The fresher and
lighter water cannot balance an equal bulk of salter and heavier water.
When once currents are started the revolution of the earth upon its axis
would affect them, just as the rotation of the earth affects the
trade-winds. Now, all these various agencies, and perhaps many others,
combine their influence to destroy the equilibrium of the waters of the
ocean. They unite and interweave their influence in a thousand ways beyond
all human calculation. The result is the ocean currents. But how much is
due to one cause and how much to another in the present state of knowledge
no man can tell. Only for a few years have the phenomena of ocean currents
been made the object of scientific observation and research. But the
effect of ocean currents in modifying climate is well understood, and the
modification of climate means nothing else than the transfer of heat. This
is all that I have to say of the rivers of the sea, and if there are no
more questions, we will now look at the movement of heat caused by
icebergs."

No question was asked, and Mr. Wilton continued:

"In polar regions there must be an immense formation of ice. Except in the
oceans, the movements of water are chiefly movements of water in the
condition of ice. Only for a small part of the year could water exist
unfrozen. Immense regions of the Antarctic continent seem to be covered
with one broad glacier. The ice pushes down into the sea until,
undermined by the dashing of the waves, it breaks off, and enormous
fragments are launched upon the deep waters. Sir James Ross saw in the
southern ocean a chain of such icebergs extending as far as the eye could
reach from the mast-head, many of them from one hundred feet to one
hundred and eighty feet in height and miles across. Captain d'Urville saw
one thirteen miles long and one hundred feet high. Its bulk was so vast
that though the waves were dashing against it not a tremor was
perceptible. Astronomic observations could be made from it as if it were
solid rock rooted in the heart of the earth. In the same manner icebergs
are formed in the northern ocean also. How much heat is given out in the
freezing of water?"

"About one hundred and forty degrees," answered Peter.

"In the formation of icebergs, then, heat is given out nearly sufficient
to boil an equal quantity of cold water. The icebergs float away toward
the equator. They come down from Baffin's Bay till they meet the Gulf
Stream off Newfoundland. In the southern hemisphere they come ten degrees
nearer the equator. As they float toward the tropics they slowly melt, and
in their melting they exact from the air and the sea where they melt the
same amount of heat which they gave up in their freezing. If they melted
at the same place where they froze, there would be no transfer of heat.
But they are formed in the polar regions; they give out their heat in the
frigid zone, while they melt and absorb a like amount of heat from the
temperate zones. In this manner the polar regions are exchanging with the
temperate zones ice for water. They borrow water, rob it of its latent
heat, and send it back in the form of ice. The temperate zones supply the
needed heat and bring the ice back to the form of water, when the polar
regions again borrow it, seize upon its heat, and again send it back in
the form of ice mountains. The effect is the same as if thousands of
railroad trains were transporting water to the frigid zones, leaving it
there to freeze and give up its one hundred and forty degrees of latent
heat, and bringing it back in the form of ice. Let us estimate the bulk of
one such iceberg as that seen by Captain d'Urville. It was thirteen miles
long and one hundred feet high, and we will suppose that it was four miles
broad. Standing out from the water one hundred feet, it must have sunk at
least eight hundred feet below the surface. This would give us the
enormous bulk of (1,304,709,120,000) one trillion three hundred and four
billions seven hundred and nine millions one hundred and twenty thousand
cubic feet of ice. The burning of one pound of coal will generate heat
sufficient to melt about five and a half cubic feet of ice. To melt one
such iceberg would require more than one hundred and eighteen millions of
tons of anthracite coal. This is the amount of heat given out in the polar
region by its freezing. This is the amount of heat transported from the
warmer to the colder regions. But what is one iceberg to the thousands
which drift yearly from the frigid zones toward the tropics?

"But even this hardly represents the entire transfer of heat by the agency
of icebergs. The icebergs are formed from the snows of polar storms, and
these are formed from the condensation and freezing of vapors. In the
process of condensation one thousand degrees of heat are given out. Every
iceberg _represents_ a transfer of heat sufficient to boil more than six
times its weight of ice water.

"One marked illustration of the effect of icebergs we ought to notice.
Down through Baffin's Bay icebergs are constantly floating. They are borne
on southward till, in the still waters of the Grand Banks, between the
polar current and the Gulf Stream, they float around and melt and
disappear. To these melting icebergs the chilliness and unfailing fogs of
the Grand Banks are due; and not only this, but the very existence of the
Banks is supposed to be due to the deposit of sediment, sand, earth, and
stone brought by polar ice.

"I have spoken only of the polar glaciers and the icebergs formed by their
pushing off into the sea. But the same transfer of heat is taking place,
on a very much smaller scale and within narrow limits, by the glaciers of
the Alps and every other mountain glacier. The glaciers are nothing else
than rivers of ice. Snow falls upon the mountain tops and valleys of the
mountain sides from age to age. The snow slowly changes to the structure
of ice, and by its enormous weight flows down through the gorges of the
mountain sides, till in the warmer vales below it melts and disappears.
We have not time to go into a full examination of all the interesting
phenomena of glaciers, but this one point you will notice and remember:
these rivers of ice--for they flow like rivers--cool the valleys and tend
to warm the mountain tops; of course upon the tops of the mountains there
can be no accumulation of heat, because, standing out into the eternal
coldness of space, and swept by winds for ever, and exposed by the
thinness of the air to a rapidity of evaporation unknown at the sea level,
heat is caught up and borne away in a moment.


[Illustration: TRANSPORTATION of HEAT.

Page 288.]


"This closes this department of our theme. I might have gone much more
into details and given you great stores of particular facts and figures,
but they would have added nothing to your understanding of the subject,
and we can hardly afford to devote our Lord's Day to mastering the details
of the natural sciences. We have now looked at some of the methods by
which the extremes of heat and cold, in day and night, in summer and
winter, and in the tropics and polar regions, are mitigated. The same
principles operate upon the smallest and upon the largest scale. If there
is need for me to attempt in a formal way to awaken in you admiration for
the wisdom and goodness of God shown in all these beneficent arrangements
for equalizing temperature, our study has been largely in vain. We have
only to remember that all these contrivances are the Lord's designs. He
created the world; he endowed matter with its qualities and forces, and he
gave it these qualities and forces for the purpose of using it as he has
used it. He planned all those contrivances by which he secures the comfort
and the good of man, and the fact that these natural agencies are fitted
for moral uses in recovering sinners to holiness and blessedness is but
the culmination of its adaptation to the uses of man.

"This, however, does not complete our course of study. A few other points
will demand our attention for two or three more lessons. But while we go
on with our studies of Nature, remember that the physical was created for
the sake of the spiritual; the spiritual is more important. Let us not
subvert the divine order and sink the high purpose of the creation to mere
material agencies and contrivances. To know God is greater and better than
to understand Nature. That we might know and enjoy and glorify the
Creator was the object of our creation. We cannot express it in better
language than that employed in the old catechism: 'The chief end of man is
to glorify God and enjoy him for ever.' That term 'for ever' includes the
present life as well as the future. We ought to know, enjoy, and glorify
God to-day. I hope that another week may find Ansel with some happy
experience in this matter."



CHAPTER XIV.

COMBUSTION.--COAL-BEDS.


Another Lord's Day comes, and no change has taken place with the class
which calls for mention. Ansel still walks in darkness, ready indeed on
every occasion to manifest his concern for the salvation of his soul,
diligent in reading the Scriptures, frequent in prayer, and giving yet no
indication of a flagging of his avowed purpose to follow Christ, but he
receives no comfort and peace. A painful and distressed interest is
becoming more and more concentrated upon him. What will be the end of his
groping in darkness? This cannot last always. Unless the hindrance,
whatever it be, which prevents the exercise of faith, be seen and removed,
Ansel will probably soon go back to his former careless state, and, it may
be, become tenfold more obdurate than before. He will be likely, on the
one hand, to become self-righteous from his supposed effort to come to
Jesus, and, on the other, discouraged and despairing, feeling that for him
effort is vain and salvation unattainable. While he remains in this state
the very lapse of time is dangerous. All feel concerned for him, but no
questions are asked, and the lesson goes on as usual.

"The method of transferring heat which we are now to examine is wholly
different in principle from any which we have as yet considered. I refer
to the production of heat by combustion. The transfer of heat by
combustion cannot be compared for vastness with those great movements of
heat which have before claimed our attention, yet for the comfort and
well-being of the human race combustion is exceedingly important. Without
that command of heat which combustion gives, man could not rise at best
above the savage state, and in fact could hardly exist upon the earth. We
smile at the Grecian myth that Prometheus stole fire from the gods and
brought it to men in his reed staff, but fire is certainly worthy of being
counted one of God's great gifts. But whence comes the heat of combustion?
Is it a new and original generation of heat, or is it merely a transfer?
Will some one explain this?"

"I don't think that I can tell," said Samuel. "I remember the principles
you have given us about the nature and production of heat, but I do not
know how to apply them to combustion."

"I did not suppose that you would be able to explain all the phenomena of
Nature at sight, yet the production of heat by combustion is not difficult
to be understood. The burning of wood and coal is chiefly the union of
oxygen with carbon. The oxygen of the air unites with the carbon of the
combustible. The attractive force between oxygen and carbon is very
strong. When they unite, the atoms of oxygen dash against the atoms of
carbon with great violence. As they dash one upon another their motion is
lost, but by the laws of transmutation of forces that lost motion
reappears as heat; that is, the motion of the atoms as they fall the one
against the other is changed to that vibration of the atoms which we call
heat. The atoms of carbon, in their separation from oxygen, may be
compared to weights suspended, ready to fall. Let once the cord be cut,
and the weight falls and dashes against the earth; its motion in falling
is lost, and reappears as heat. So carbon is suspended, so to speak,
waiting to unite with oxygen. But how is the weight raised? How is carbon
brought into this state of suspense, waiting to dash upon oxygen and
develop heat? That is not its natural state.

"Carbonic acid is found everywhere mingled in small proportions with the
atmosphere. This carbonic acid is nothing else than carbon and oxygen
united in the proportion of one atom of carbon to two atoms of oxygen.
This is the natural state of carbon. This carbonic acid is the food of
plants; it is this which supports all vegetable growth. The carbonic acid
is absorbed by the leaves of plants and trees, and in the hidden
laboratory of the leaf, by what process is one of the undiscovered secrets
of Nature, the carbon is separated from the oxygen, the oxygen is
discharged through the pores of the leaf, and the carbon is carried into
the circulation to build up the fabric of the woody fibre. That which the
most skillful chemist in the world cannot do, except by indirect processes
and at a high temperature, the leaves are doing directly at the ordinary
temperature. Vegetable growth is a deoxidizing process. To accomplish this
an enormous force is requisite. To separate carbon and oxygen, a force is
demanded which is able to overcome their powerful attraction. How shall we
estimate the strength of this force? In order that they may unite, as in
the explosion of gunpowder, solid rocks are torn asunder. The attraction
of carbon and oxygen is strong enough to tear great rocks in twain. It is
this attraction which sends the cannon ball and the shell like meteors of
death upon their errands of destruction. This great force must be
overcome; carbon must be separated from oxygen and built into trees. This
is the lifting up of the weight. But whence comes the force necessary to
accomplish this? From the sunbeam. The heat of the summer's sun, employed
as force, is used to deoxidize carbonic acid. Heat is used, and used up,
in lifting the weight which in its fall shall generate again a like amount
of heat. The combustion of wood produces the same amount of heat as was
needful to separate its carbon from the carbonic acid of the air.
Vegetable growth is thus a cooling process; heat is withdrawn from use as
heat, and is employed as force. As force it has nothing to do with
temperature. The summer's heat, employed in vegetable growth, reappears
in the blazing billets of the kitchen fire. Heat is condensed and
solidified, so to speak, and placed under man's control. In this
solidified form heat may be laid up in store or transported at pleasure.

"The grandest application of this principle is seen in the formation of
the coal-beds. At some early period in the unmeasured ages past, the
temperature of the earth must have been much higher than it now is; the
air was filled with moisture, and carbonic acid abounded. As a
consequence, there was an enormous vegetable growth. This, as we have
seen, is a heat-consuming process. The heat is withdrawn from the air and
employed in deoxidizing the carbonic acid. This vast vegetable
growth--enormous ferns and coniferous trees--fell, and was swept by rivers
or by floods into valleys, or the beds of lakes, or the sea; the sediment
of the waters covered it, and there, shut up from the air and subjected to
a heavy pressure, this vegetable mass underwent a slow transformation.
Peter, have you ever seen a coal-pit? I do not mean a coal _mine_, but
that which charcoal-burners call a coal-pit."

"I have seen them many a time."

"Tell us, then, how wood is burned to coal without being burned up."

"The wood is set on end, closely packed in the shape of a mound, and then
covered with earth. Fire is kindled in the middle of the pile, and just
enough air admitted through air-holes at the bottom to keep up a slow
burning. It burns just fast enough to heat and dry the wood without
burning it up."

"The same process," said Mr. Wilton, "went on in the formation of the
coal-beds, but very much more slowly. Under the pressure of earth and
water the vegetable deposits lie smouldering, not for a few days, but
probably for ages, till nothing but the carbon remains, and that pressed
into a solid mass heavy as stone. Veins of coal are found interspersed
with layers of earth and rock, layer above layer, and these layers are
commonly not level, but more or less inclined and sometimes broken. This
shows that a deposit of driftwood was made, then a deposit of sand or
clay, then another deposit of vegetable material and another layer of
earth. At length, by internal convulsions, the whole surface was raised
from beneath the waters, and in due time the coal-veins were laid open,
and the coal brought out for the use of man. Then the force so long pent
up and held in suspense is set free; the stored-up heat of the geologic
ages is brought out for use. The excess of heat in that ancient period is
handed down to these later times. How sublime this transfer of heat! It
carries us back, in imagination, to the 'heroic ages,' so to speak, of the
history of creation. By other methods heat is treasured up for a day or a
year: by this method it is kept in store for myriads of ages. We see that
the same natural forces were working in those early ages as to-day, and
the same benevolent Creator was arranging the affairs of the world for
man's advantage. The sunbeam which streamed upon the earth long ages
before man was created is to-day smelting ores, driving machinery,
dragging ponderous trains of loaded cars, and ploughing the seas with
freighted keels. This seems like a fairy-story or a dream, but instead of
that it is the soberest of philosophic and scientific truth.

"We ought also to notice the internal heat of the earth. This has been
handed down from the day of creation, it would seem, till the present. No
new principle is seen in the earth's internal fires, but a sublime
illustration of the storing up of heat in a hot body and its slow
radiation.

"The origin of the internal heat of the earth we can only conjecture.
Perhaps God created the various elements separate, uncombined, and allowed
them then to combine according to their natural affinities. This sublime
conflagration of all the elements of the earth would generate the highest
temperature which could be produced by combustion. The elements would melt
with fervent heat; everything which could be vaporized by heat would be
turned to vapor. Then radiation of heat would begin. Vapors would sink to
fluids and fluids turn to solids; a hard crust would be formed on the
surface of the globe through which the heat of the still molten mass
within would be slowly conducted and escape. Upon this internal heat the
earth depends in no small degree for its temperature. The heat generated
perhaps upon the day of creation helps now to render the earth habitable.

"That the earth was once in a fluid state and has lost a portion of its
heat by radiation is indicated by several facts. It is one of the received
beliefs among geologists that at some period in the past the temperature
of the earth was much higher than it now is. The animals and plants which
flourished during the ages when the coal-fields were deposited show that
sea and land were warmer than at present. It is believed that the change
of temperature has taken place on account of the cooling of the earth from
radiation. The rate of radiation is so slow, however, that no farther
sensible change of temperature can take place for thousands of
generations.

"The form of the earth also indicates that it was once fluid. The earth is
an oblate spheroid, a flattened sphere, and has that degree of flatness
which a fluid mass would assume if revolving at its present rate. The
earth swells at the equator and rises thirteen or fourteen miles above the
sea level at the poles. The waters of the ocean move freely and take the
same form as if the whole globe were fluid, and the solid parts of the
earth have the same degree of convexity, which shows that it took its form
from its own rotation upon its axis while in a fluid state. This would
also show that in the primal ages, when the earth was in a plastic or
fluid state, it had the same rate of rotation as at present.

"The lifting up of the mountain ranges also is best explained by
supposing that the earth was once molten. The earth cooled, a crust was
formed, and by farther cooling and contraction of the molten mass within
the crust wrinkled and formed mountain chains. Thus the higher temperature
of the geologic ages, the form of the earth as if it were a revolving
fluid mass, and the corrugation of its surface--these, joined with its
present internal heat, point to the fact that it was once molten and fluid
to its surface. The benefits of this heat laid up in store on the day of
creation we still enjoy."

"Before the class is dismissed," said Mr. Hume, "I should like to say a
few words."

"I have nothing farther to say to-day," answered Mr. Wilton, "and we
should be glad to hear you now. Say on."

"I wish only to say that these lessons have led me to such thoughts of
God's wisdom and goodness as I never had before. Of course it is not
strange that this should be the case with me. I now look at everything
with new eyes. It is not merely this one element of heat in Nature that
moves my admiration, but I have been led to consider a thousand things in
which the goodness of God is shown. My thoughts of the divine goodness
are as fresh and interesting to me as my impressions of his righteousness
and holiness are startling. For years I have tried with might and main to
look upon the dark side of the world and to exaggerate its physical evils.
I have searched for disorder and want of adaptation. As long as I
misunderstood the purpose of the creation, I thought I was successful in
impugning the wisdom of the arrangements of this physical world. While I
supposed that the earth must needs be the Creator's masterpiece in beauty
and pleasantness and all manner of perfections, designed just to give
sensual pleasure to its inhabitants, I could find, or thought I found,
many faults in the Creator's work. Now I withdraw all my former charges.
My eyes are opened. The rougher elements of man's life will henceforth
have a new meaning to me. I see that God seeks not so much present
pleasure for men as their holiness. He lays a solid foundation for their
happiness. He seeks to render men blessed by bringing them into likeness
and union with himself. These are new views to me, and I thank my heavenly
Father that this new light has dawned upon me. I feel now that I can bear
the ills of this life cheerfully, understanding that the Lord is using
them as a means of spiritual discipline. It seems to me as if this lower
world and man's lowly life were already glorified by a beam of light
falling from heaven. I hope that my young friends have been as much
profited as I have been."

"I rejoice with you, Mr. Hume. 'We know that all things work together for
good to them that love God.' This light has shone upon me for many
years."



CHAPTER XV.

ECONOMY OF HEAT.


"In this final lesson I wish," said Mr. Wilton, "to bring before you some
general views of the whole subject of the agency and management of heat.

"When Jesus had fed the five thousand men upon the mountain side by the
Sea of Galilee, he said to his disciples, 'Gather up the fragments that
remain, that nothing be lost.' The Christ who spoke these words was the
same Christ by whom 'all things were created that are in heaven and that
are in the earth, visible and invisible.' These words inculcate the
propriety of saving, the very opposite of extravagance and wastefulness.
The same prudent economy we find in all God's works. Nothing is wasted.
God provides bountifully; he is not stinted in his works; we find nothing
narrow or mean; his resources are ample for all his undertakings. Perhaps
a careless observer might charge him with prodigality and wastefulness.
The wilderness rejoices in beauty and fertility upon which no human eye
gazes, and which supplies no human want.

    'Full many a gem of purest ray serene
      The dark unfathomed caves of ocean bear;
    Full many a flower is born to blush unseen,
      And waste its sweetness on the desert air.'

Rich fruit grows ruddy and golden in the autumnal sun only to fall and
decay. How small a part of the seeds which might germinate and reproduce
the parent plant ever fulfill this their legitimate object! But this is
not waste. As for the beauty with which the unpeopled wastes are smiling,
we know not what other beings besides man 'grow glad at the sight.' Fruits
and grains and seeds were appointed as much to nourish the animal kingdom
as to reproduce plants and trees. And that which decays is not wasted. The
oak lifts high its leafy arms and does battle with the tempests for a
century, and then having served its purpose in Nature, if man does not
call it to the higher mission of serving his purposes, Nature begins to
pull down the structure she has reared and rebuild the elements in other
forms--such forms as man perchance may need. The fruit that falls and
decays is not wasted; it shall blush with golden tints in other forms and
in other years. God pulls down the old that he may build the new. The same
elements appear and reappear in a thousand shapes. There is endless
change, but no waste. This sentiment, 'Gather up the fragments, that
nothing be lost,' which is proclaimed throughout all Nature, is uttered
most emphatically in the management of heat. God has provided most
bountiful stores of heat, but has left no heat to go to waste. Will you,
Mr. Hume, suggest one of the general arrangements for the economical use
of heat?"

"I think that the arrangement for economizing heat which ought to be
mentioned first is the confinement of heat to the locality where it is
needed."

"Will you explain that a little farther, Mr. Hume?"

"All living creatures are confined near the surface of the earth. They
penetrate only a few feet into the earth and soar a few hundred feet above
it. Heat is therefore confined to the region of the earth's surface. It
penetrates but a little way below the surface, and when warm air rises
into the higher regions, heat becomes latent. The higher parts of the
atmosphere are cold, and in the empty spaces of the heavens the
temperature is we know not how low. God has provided for heating only that
part of the world which needs to be heated. I think you spoke of this in
some one of the earlier lessons."

"Perhaps I did. But I refer to it again to call especial attention to the
idea of the economical use of heat. Who will mention another method by
which heat is economized?"

No one answered.

"I asked the question, but did not expect an answer. God shows economy in
the use of heat by accomplishing many different results by its agency. I
do not mean that the same identical heat accomplishes different results at
the same time. The same force cannot accomplish two works. As man cannot
spend his money and at the same time keep it, no more can heat be used and
not used up in that form. The heat which raises the temperature can do
nothing else at the same time, and when it is employed as force it ceases
to affect temperature. But by this one agency of heat the Creator brings
very various works to pass. Heat expands bodies, relaxes cohesive
attraction, and brings the chemical affinities into activity. By this
means the elements of Nature are subdued to human uses, seeds germinate,
all the processes of vegetable life go on, and digestion and nutrition are
carried forward in the bodies of animals. By the agency of heat the winds
blow, the deep waters of the ocean circulate, clouds are formed, dew and
rain refresh the earth, rivers flow, and all the activities of life fill
the world. The employment of one agency for the accomplishment of so many
works indicates economy in the expenditure of force and means. Moreover,
the same heat appears and reappears again and again, passing from the
sensible to the latent form and back again, asserting itself alternately
in raising the temperature and as active force. A beam of heat falls upon
our world: it is partly absorbed by the earth, and warms it. A part of
that warmth is used in setting the chemical affinities in action in the
sprouting of seeds; a part warms the air by conduction; a part is
radiated, and being stopped by the vapor in the air, warms it; the heat
of the air is partly used in the evaporation of water: the vapor formed is
condensed and waters the earth, and gives out the heat by which it was
formed; that raises the temperature of the air; a part of it is used in
deoxidizing carbonic acid and building up the forests; the forest tree
falls by the woodman's axe, is burned for fuel, and gives out its heat
again, or if it falls and decays, the result is the same; the heat given
out by combustion cooks the laborer's dinner and warms his room, or it
goes out again, and is used in preparing food for the growing wheat; that
wheat is used for food, and by slow combustion in the blood the heat is
again evolved, the body is warmed, and the chemical operations of
digestion and nutrition are maintained; the heat is radiated or conducted
from the body into the atmosphere, and again raises the temperature and
goes to do other work. At last, so far as our earth is concerned, it
escapes into the stellar spaces, and goes to bless other worlds. In all
these operations no heat-force is frittered away and wasted and lost. This
is one of the accepted doctrines of physical science. Heat is used
bountifully, but economically and without waste.

"Even the inequalities and variations of temperature must be counted
economy in the use of heat. The heat of midday is not needed at all hours,
and therefore it is not always provided; the heat of summer is not always
useful, and is therefore not given; a higher temperature for a part of the
year and a part of the day is necessary, and is bestowed. The smallest
amount of heat is so disposed as to accomplish the largest result. Keep in
mind, then, the economical aspect of God's management of heat.

"I would also have you remember how few are the principles involved in all
the ways and means for transporting heat and equalizing temperature. All
the various phenomena which we have examined can be brought under two
general principles. The first principle or method is the heating and
cooling of bodies. Bodies absorb heat; they part with their heat by
conduction or radiation. If they are heated and cooled without change of
place, heat is transported in time, but not in place. If the body be
removed from one place to another between the heating and the cooling or
between the cooling and the heating, heat is transported in both time and
space. This applies alike to solids, liquids, and gases; each one is a
carrier of heat in proportion to its specific heat.

"The second principle or method is the transportation of heat by the
change of sensible to latent heat and its restoration to a sensible state.
Under this principle there are four cases:

"1. Heat is employed in the evaporation of liquids, and is restored again
to use as affecting temperature by the condensation of the vapor.

"2. Heat is employed in liquifying solids, and becomes latent thereby, and
returns to the sensible state when the liquid solidifies. These two
principles find their grandest application in the changes of water: of
this application I have chiefly spoken; but they apply also to other
bodies--to metals as well as to liquids.

"3. Heat is rendered latent in the expansion of gases from removal of
pressure, and latent heat becomes sensible by the compression of gases.

"4. Heat is employed in the deoxidation of carbonic acid or other
combinations of oxygen, and is evolved in combustion. While in the latent
condition, heat may be kept without loss for an unlimited period of time
or transported from equator to pole. By the various applications of these
two general principles, all the different methods of equalizing
temperature are determined.

"I would have you remember also that these processes for transporting heat
and modifying temperature are not confined to the regular changes of days
and seasons and the permanent differences of zones, but apply to every
possible difference of temperature. One minute the sun shines out in full
splendor; the next, a cloud hides his face and cuts off his fervent beams;
the methods employed to soften the heat of the one minute and the chill of
the next are the same which equalize the temperature of the seasons.
Evaporation carries off the heat from the seething tropics, evaporation
carries off the excess of heat from the bodies of animals and men. The
same methods are equally efficient upon the grandest and upon the smallest
scale.

"In this connection let me give one or two illustrations of the delicacy
with which general principles adapt themselves to the minutest
circumstances. When the earth is wet, it is fitting that evaporation
should go on rapidly and remove the excess of water, but when the ground
is drier, it is fitting that evaporation should be checked and the
remaining moisture spared. This result is secured not merely by the lack
of moisture at the surface, but also by the decreased capacity of the
earth for absorbing heat. A dark color absorbs heat more readily than a
lighter color, and the earth becomes, as a general rule, darker when wet;
and lighter when dry. Moist earth, therefore, receives heat more readily
than dry earth, and the excessive moisture is the more rapidly carried off
by evaporation.

"Another more interesting illustration is presented by the odor of
flowers. In its place I told you that watery vapor hinders the radiation
of heat from the earth. Dark heat is absorbed by it. The same is true of
other gases, and also of the odors of fragrant substances. A bed of
flowers fills the air around with odors. By these odors much of the heat
radiated by the earth is stopped. By this means the air around the
blooming flowers is warmed. The invisible fragrance raises the temperature
and secures for the blooming plants a more genial atmosphere. The Lord
provides for the flowers when most of all they need to be cherished by a
congenial warmth.

"This completes what I have to say to you upon the subject of heat. I
might have gone far more into particulars, and extended these lessons over
six months instead of three. We started with the design of finding out
whether the works of Nature have anything to say about a wise and good
Creator. We could not examine the whole circle of God's works, and
therefore chose a single department--that of heat. I will leave yourselves
to decide whether we have found marks of divine wisdom and goodness,
whether Nature has had anything to say to _us_ about a Creator."

"It seems to me," said Samuel, "that if the works of Nature do not show
God's goodness and wisdom, it would be hard to tell what works would show
them. I think I shall always, after this, look upon the earth and sky with
more interest than I have ever felt in them before; I shall always look
upon them as having something to do with God."

"We certainly ought," said Mr. Wilton, "to study Nature in such a manner
and with such a spirit that we shall be led to reverence and worship the
Creator. Some very good men are afraid of scientific study, as if there
were something in it to draw men from belief in the Scriptures and the
Jehovah revealed in them; and it cannot be denied that not a few
unbelievers have tried to find a foundation and a defence for their
infidelity in scientific studies; but such men are not made skeptics by
earnest and reverent study of God's works: they were unbelievers before
and aside from physical studies, and they only try to glorify their
rejection of the Bible and Christ by deifying science and the creation and
holding them up in opposition to inspired revelations. If ever you find
the works of God separating you from God, you may know at once that you
misunderstand those works or come to them with a wrong spirit. 'The
undevout astronomer,' it has been said, 'is mad,' and the same might, with
good reason, be said of every undevout student of physical science.

"In selecting heat for our examination, I did not take the only rich
department of Nature's works. The practical chemist would find a richer
and broader field of research, and so would the anatomist and animal
physiologist, the geologist, or the physical geographer. I purposely chose
a comparatively narrow field, in order that our course of study might not
become wearisome by its length. You will find ample scope in the fields of
natural science for your largest powers, and enough to carry your thoughts
reverently to the great Creator and Governor.

"In one respect the study of Nature resembles the study of the Sacred
Scriptures. It is a revelation; it is an embodiment of God's thoughts; in
it God has expressed himself; and Nature, by most suggestive symbols and
types, teaches much more moral truth and spiritual sentiment than some men
think. In the brute creation it gives us, in pantomime, all the virtues
and graces and all repulsive vices and cruel passions. To this book of
Nature we ought to come without prejudice, reverently inquiring what is
written therein. We must study it thoroughly and interpret it as we
interpret the written word, comparing Scripture with Scripture. It is a
great attainment to be able to read and understand the thoughts of God
embodied in his works.

"In another respect, the book of Nature and the Sacred Scriptures have
very little in common. The Bible is occupied pre-eminently with moral
duties and spiritual relationship. Its great themes are sin and salvation.
Christ is the great central truth. One might compare the Scriptures to a
picture in which one central figure seizes every eye, and by whose
radiance the whole picture is filled with light, and that central figure
is Christ; or we might compare the Bible to a sublime oratorio, the
glorious symphony of the ages; through it all is heard one strain, sweetly
exultant as angel voices, faintly heard at first amid the sadness of the
fall, but rising still above the terrific bass of Sinai and its
ever-repeating echoes, growing more clear and strong upon the harps of the
prophets, till its rapturous beauty pours itself triumphant along the
plains of Bethlehem. In this revelation of salvation from the guilt and
ruin of sin the Bible stands alone. Upon this subject Nature is silent.
Salvation by Christ is the gem enshrined in the Scriptures. But what is
the setting for this gem? The works of God on the earth and in the
heavens. The prophets were men in sympathy with Nature. How David sung the
praises of the divine handiwork!--'O Lord, how manifold are thy works; in
wisdom hast thou made them all.' 'The heavens declare the glory of God
and the firmament showeth his handiwork. Day unto day uttereth speech, and
night unto night showeth knowledge. There is no speech nor language where
their voice is not heard.' How Christ unfolded the deepest spiritual
truths by the symbols of Nature! But if the casket be so worthy, what
shall be said of the gem which is enshrined within? That is the pearl of
great price. To that book which speaks in no doubtful voice of deliverance
from sin let us turn with increasing reverence; and above all, let us come
to him who came to reveal our God, who came to be as well as to make a
revelation of God, being himself 'the brightness of his glory and the
express image of his person.' I am glad that you all now feel that you
know him whom to know is everlasting life."

From these words of Mr. Wilton you will conclude that Ansel has at length
found rest in Christ. In another brief chapter I will tell you of his
experience, and then bid you adieu.



CHAPTER XVI.

A DAY OF JOY AND GLADNESS.


The reader has already learned that after Ansel had confessed himself an
anxious inquirer and professed himself willing to obey Christ, he remained
three or four weeks still in darkness. Others found peace in believing,
but he felt no joyful confidence that Christ had received him and forgiven
his sins. He sometimes felt almost discouraged, and sometimes was tempted
to complain of God for not treating him as favorably as others, or to feel
chagrined because others were rejoicing, while he found no light. But he
fought against these evil thoughts and insinuations of Satan, and did not
flag in his private devotions or cease to confess himself, always and
everywhere, an anxious inquirer, still in darkness, but desiring to find
the grace of God. If ever he was tempted to push away all concern about
salvation and return by force to his former careless state, the words of
Christ would come to his mind: "Will ye also go away?" and Peter's answer,
"Lord, to whom shall we go? for thou hast the words of eternal life." The
alternative, salvation by Christ or the loss of his soul, stared him in
the face.

    "I can but perish if I go;
      I am resolved to try;
    For if I stay away, I know,
      I must for ever die."

Great interest was felt for him and much prayer was offered in his behalf,
but he seemed to make no progress toward a better state. Mr. Wilton had
talked with him, but had failed to discover what it was that hindered his
humble acceptance of the grace of Christ. After long and anxious musing
upon Ansel's character and surroundings and the previous conversations
which he had had with him, Mr. Wilton determined to probe him more fully.
For this reason he invited Ansel to his study, where the following
conversation transpired:

"Good-morning, my young friend; how do you find yourself to-day?"

"I am feeling, I think, very much as when I was here a week ago."

"Are you becoming discouraged and almost ready to give up all effort to
follow Christ?"

"I do sometimes feel very much discouraged, but I am not ready to give up
my interest in religion."

"Have you no more enjoyment in reading the Scriptures and in your prayer
in secret than you had a week ago?"

"I think that I am trying to do right in doing these things, and I enjoy
them better than I should if I felt that I was doing something wrong, but
I do not feel as I think a Christian ought to feel."

"Are your thoughts and feelings and opinions about Christ and salvation
the same as they were six weeks ago?"

"I think they are very different."

"I am glad to hear that; but can you tell how they are different?"

"At that time I felt that I was a sinner, but was fighting against that
feeling. I wished that Christ would let me alone, and that the Holy Spirit
would not trouble me. But now I very much wish that I may feel my sins,
and that Christ may come to me and save me. I wish to follow the Spirit."

"Did you expect a month ago that at this time you would be feeling and
acting as you now feel and act?"

"No, sir; I meant then to fight it through, and not let anybody know how I
felt."

"Do you wish now that you had fought it through, as you proposed, and kept
all your feelings to yourself?"

"I am very thankful that I did not keep on hiding my feelings. I almost
tremble to think what the result would have been."

"You have said that you wish to spend your life in serving Christ. Does it
seem to you a hard and painful work--a work that you would get rid of if
you could--or does working for Christ and confessing Christ before men
seem attractive?"

"I think his service seems pleasant; there is no other life that seems
half as pleasant."

"Do you believe that Christ is able to save you?"

"I suppose he is. If he cannot save me, there is no hope for me, for I
cannot save myself."

"Do you believe that he is willing to save you?"

"I think he is, if I come to him and trust in him. I suppose he is willing
to save all who come to him."

"Are you unwilling to come to him--to trust him and submit to him?"

"I don't know; I have tried to come to Christ, but I have met with no such
change as I have always supposed that a Christian ought to have."

"What do you think it is that hinders your coming into light and joy as
others have done?"

"I cannot tell. I suppose it must be something or other in myself, but I
cannot guess what it is."

"I would like to ask you a few questions which you may think rather close
and personal, and which you may find it hard to answer frankly. You know
the spiritual adviser, as well as the physician, must first of all find
out the condition of the patient."

"I am willing to have you ask any questions you please, and I will try to
answer them as well as I can."

"Did you ever think, Ansel, that you were very ambitious?"

"I knew that, like many others, I was a little ambitious, but I never
thought that I was very much so."

"Perhaps you were more ambitious than you thought. You know that you would
work day and night rather than not stand at the head of every class you
were in. On the play-ground you asserted your position as leader in every
game. Did you not carry the same idea of being chief into your plans and
expectations for the future? You were ambitious of standing the very first
whatever course of life you might follow. Was not this so?"

"I don't know: I can't deny it; I think it was."

"It is possible, Ansel, that you are trying to carry the same ambition
into the kingdom of Christ. Perhaps you have wished in conversion some
brilliant experience which would draw attention to you. Tell me how this
is. Would you be satisfied to have a commonplace experience, such as
thousands of others have, which would attract no special notice? Have you
not formed an idea of the great and brilliant change you must pass
through, and are you not refusing to take anything else from the Lord's
hands?"

Tears gathered in Ansel's eyes, and his face worked painfully. At length
he answered: "Your question is a hard one to answer, but I cannot deny it;
I am afraid it is so. I have heard persons tell of the great load of sin
like a pack on their shoulders, and of the earth seeming as if it would
open and swallow them up, of sleepless nights and unspeakable anguish, and
then of light and joy, so that they could never doubt that they were
converted. I have been expecting that I was to have such an experience,
but I have not seen it. Is it wrong to wish for such an experience?"

"It is certainly wrong to _insist_ upon such an experience. God leads each
one to himself in his own chosen way. There was but one Saul, whom Christ
met and blinded with the dazzling light. As a general rule, when a sinner
makes up his mind in what way he will be converted, the Lord will
disappoint him. If he fixes in his mind that he will not come to an
anxious-seat, or will not confess his feelings till he can say that his
sins are pardoned, or will not do anything else, the Lord will very
likely bring him to do the very thing he resolved that he would not do.
If he attempts to bring his ambitious aspirations into Christ's kingdom,
he will be disappointed. 'The first shall be last and the last first.' Men
become great in Christian service by counting themselves the least of all,
and humbling themselves to become the servants of all. You need to examine
yourself in this matter. If you have looked for something great and
startling, be contented with something small and commonplace. It is an
unspeakable privilege to be brought into Christ's kingdom in any manner.
It is sometimes a great blessing to have a very unmarked and plain style
of conversion. Such a convert is compelled to look to the truly scriptural
evidences of a change of heart instead of resting upon the evidence, often
deceptive, of a great and sudden illumination or a fancied voice from
heaven. Some of the greatest and best of men have been unable to tell at
all the time of their conversion. Richard Baxter could not tell even the
year of his change. The best experiences I have known have been those
where the converts could tell very little about themselves; they had been
doing something else besides looking into themselves to watch the motions
of their own thoughts."

"I will try to do as you say. But what kind of evidence am I to look for?"

"The same kind of evidence which you now look for in me or any other
Christian. It is not one thing to come to Christ and another thing to
follow Christ. The best evidence that a sinner has come to Christ is that
he actually follows Christ and serves him. 'By their fruits ye shall know
them.' 'Bring forth fruits meet for repentance,' said John the Baptist.
Bring forth fruits that show that your thoughts about sin, and about
Christ, and about the service of Christ have been changed. Look for the
same kind of evidence in yourself that you would look for in any stranger
whom you should meet. But above all things take the words of Jesus as true
and rest on them; consecrate yourself to Jesus with all the heart; with
lowliness of mind hold yourself ready for any work or any sacrifice; you
will find that evidences will take care of themselves. When men come into
sympathy with Christ, when they believe his words, walk with him, and talk
with him, and bear the cross with him, when they enter into a partnership
of service and suffering with Christ,--the Spirit bears witness with their
spirits that they are born of God."

"I will try to follow your advice, and am very thankful that you have
spoken about my ambitious spirit."

"Another caution I wish to give you. Do not think that you, by any methods
or by cherishing any spirit, are to make yourself fit to be saved. If you
are saved at all, Christ must take you as a sinner, and a great sinner. If
you get rid of your spirit of pride, it will be by Christ's saving you
from it. Let me also suggest to you that which a consideration of your
associations suggested to me, that you may have stumbled at the idea of
baptism. You must have heard baptism spoken of very disrespectfully, and
it is possible that you may have learned to look upon it as a humiliation
and a reproach. You may have recoiled from the thought of submitting to
it."

"That was my feeling once, but since I have been willing to have my
feelings known I have ceased to be afraid of what those who despise
religion may say."

"Be careful now, since you feel that your sympathies are with the
Christian band, that your love of greatness does not lead you to resist
the Spirit. Be willing to be small. Be thankful for small gifts. I trust
that your present feelings will before long give place to a humble trust,
a childlike confidence, and a holy boldness in Christ, and that your
usefulness in the kingdom of God will be all the greater because he now
requires you in the beginning to trample under foot your budding pride and
die to all human ambitions."

When Ansel gave up the idea of a wonderful conversion, a sudden
illumination which should bring with it something of éclat, he found that
he could understand the Scriptures better and have more enjoyment in his
religious duties. While he humbled himself, hoping for little, he found
his soul soon filled with a deep, quiet joy.

The next Saturday afternoon was the regular time for the covenant-meeting,
and also, according to custom, for hearing the experiences of any who
wished to unite with the church by baptism. Ansel, Peter, and Mr. Hume
came, along with others, to present themselves to the church. In regard to
Mr. Hume there had been much speculation among his former comrades as to
what course he would take. Some said: "Mr. Hume will never wet the sole
of his foot in that river. Don't you remember how he used to laugh at the
idea of being plunged in the river in honor of a dead man? He may talk in
meeting, but it is a very different thing to go down into the river with
the whole hillside covered with people." Others said: "We can't tell what
has come over him, but he will not go back now. He has gone too far to
retreat."

Some even ventured to approach Mr. Hume himself with their raillery:

"What do you think now of being dipped in the river in honor of a dead
man?"

"I think that I would be willing to be baptized a thousand times if I
could recall by that means what I have spoken against baptism."

"And what, Mr. Hume, about the ice water?"

"You know and I know," he answered, "that we always respected those who
did not shrink from cold water for Christ's sake. What effeminacy, what
more than effeminacy, for a resolute man to hesitate and tremble at
baptism! We should be ashamed of such weakness in any worldly matter. I
have given you occasion for all your raillery, but as I once was a leader
in evil, so I wish that I might lead you to better things."

Ansel, Peter, and the rest gave an account of their religious experiences,
and last of all Mr. Hume.

"What leads you," asked Mr. Wilton, "to present yourself to the church,
asking for baptism?"

"I think that the love of Christ leads me. I have done a great deal
against Christ, and now I wish, if possible, to do something to show my
love for him. I come to obey the word and example of Christ by being
buried with him in baptism."

They were received for baptism, and the time of administration fixed at
half-past twelve o'clock the next day.

The Lord's Day was cold and blustering. Many were disappointed, for they
hoped that the day would prove warm and sunny. But the blustering day did
not prevent the gathering of a great company by the riverside. As the
congregations left the churches they turned their steps toward the place
of baptism. Ungodly men turned out, and those who never came to hear the
preaching of the gospel flocked together to see the gospel preached by
this symbolic service. The word had gone out that Mr. Hume was to be
baptized, and this drew together his former associates. At the place
chosen the river swept around in a gentle curve and the bank rose up like
a magnificent amphitheatre; while just above, the land put out into the
water and threw the current upon the opposite side. Here gathered almost
the entire population of the village to witness that simple and solemn
service which from the days of John the Baptist has thrilled so many
hearts. The candidates came warmly clad, brought from their own homes in a
close carriage. Gathered there, the little band of Christians, surrounded
by so great a cloud of witnesses, first sang the hymn commencing:

    "Thou hast said, exalted Jesus,
      Take thy cross and follow me;
    Shall the word with terror seize us?
      Shall we from the burden flee?
          Lord, I'll take it,
      And rejoicing follow thee."

Then Mr. Wilton read with a voice that reached all the company a few
passages from the New Testament which authorized and commanded that
service. After that he prayed that the joyful presence of Christ might
attend those about to follow him in baptism, that believers might be
encouraged, and careless sinners awakened. One by one the converts were
buried with Christ, and one by one they came up out of the water,
forgetting all else in the joy of obedience. They sang the words
consecrated by use at so many riversides:

        "Oh how happy are they
        Who their Saviour obey,
    And have laid up their treasure above!
        Tongue can never express
        The sweet comfort and peace
    Of a soul in its earliest love."

These words found a response in many hearts.

High up upon the river bank were gathered a little knot of mocking
unbelievers. One among them, seven years before, had publicly professed
his faith in Christ. For a little time he seemed to be treading in the
Lord's ways, but falling among evil associates, he not only neglected
Christian duties, but became a professed unbeliever. He read infidel books
and loaned them to others. He sought to sow the seeds of unbelief wherever
he went. Upon this Lord's Day he stood with others profanely mocking at
the sacred service. With shivering, tremulous accents he exclaimed, "Poor
Harry Gill is very cold; I would not go into the water to please any
Christ for five hundred dollars." That young man went home with deep
conviction of sin upon him. Two days after, Mr. Wilton was called at ten
o'clock at night to visit him. He was trembling like an aspen leaf with
his deep anguish of conscience, and for two days and nights his body shook
under his fear. Then little by little faith took the place of fear, and
hope smiled upon him. He was the next person whom Mr. Wilton baptized.

Look in upon the Christian band assembled that Lord's Day evening. Upon
the faces of those who had been baptized there was no sign that the
service of that day had been painful; if they had done the duty as a
cross, the cross must have been quickly followed by a crown of joy, for
every face was radiant with light. Among them was one little girl twelve
years of age whose face, as she rose from the water, shone like the face
of an angel, and the transfiguration of that moment had hardly begun to
fade away. Ansel was peacefully happy, and from the face of Mr. Hume the
old look of dissatisfaction was all gone; his soul had entered into rest,
and he felt at home. Every one of them testified that it had been the
happiest day of his life. They declared themselves willing for Christ's
sake to be baptized a hundred times if he commanded. They had already
found that "in keeping his commandments there is great reward."

I should be glad, kind reader, to trace with you the Christian course of
these disciples through the years that follow. But we must leave them. I
am sure, however, that their course will be upward. Their experience was
not the mere effervescence of fickle feeling. The word of God germinated
in their hearts; they had root in themselves. They believed, they believed
the truths of the gospel, and therefore they felt, and therefore they
acted. "Whatsoever is born of God overcometh the world," and believing
that they were truly born of the Spirit, we are confident that "he which
hath begun a good work in them will perform it until the day of Jesus
Christ."





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