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Title: Leonardo da Vinci, Pathfinder of Science
Author: Gillette, Henry Sampson
Language: English
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Copyright Status: Not copyrighted in the United States. If you live elsewhere check the laws of your country before downloading this ebook. See comments about copyright issues at end of book.

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    [Illustration: _Portrait of Leonardo da Vinci, after a woodcut
    published in_ Lives of the Painters, _by Vasari. The Latin
    inscription reads_
    LIONARDO DA VINCI PITT. E SCVLTOR FIOR.
    _Leonardo da Vinci, Painter & Sculptor of Florence._]



                         _Immortals of Science_



                                LEONARDO
                                DA VINCI
                        _Pathfinder of Science_


                          _Henry S. Gillette_

                         PICTURES BY THE AUTHOR


              _Franklin Watts, Inc., 575 Lexington Avenue
                         New York 22, New York_


                           _To my wife Trudy_

                             FIRST PRINTING

           _Library of Congress Catalog Card Number: 62-8426_
                Copyright © 1962 by Franklin Watts, Inc.
             _Manufactured in the United States of America_

                       DESIGNED BY BERNARD KLEIN


AUTHOR’S NOTE

It is natural that, within the confines of these few pages, many facets
of Leonardo’s extraordinary personality will be missing. That he was an
artist, a man of letters, a poet and a philosopher are well known. That
he was also a man of humor, as well as a prophet whose vision extended
far beyond his times, are facts that I have also tried to include in
this biography. There are many gaps in our knowledge of his life, and
these I have sometimes filled with my own imagination to give some
continuity to his story. Little is known of his early days, his period
of travels after leaving Milan and his years in Rome. There is, too, a
certain mystery in his relations to those around him, since our
descriptions of him derive mostly from his often cryptic, personal notes
and from biographers who wrote of him many years after he had died.

This book is about Leonardo the scientist, and to fully write of his
many accomplishments would require an encyclopedic mind. My intent has
been to extract the essence of his story in the hopes that it would
arouse the enthusiasm of a reader to further his interest in those
other, more fully documented books—and, above all, in the notebooks that
Leonardo himself wrote.

                                                               —H. S. G.

                                                     _Rome, August 1961_



                               _Contents_


  1 _The Shield_                                                        1
  2 _Florence_                                                          9
  3 _A Studio of His Own_                                              20
  4 _Years of Frustration_                                             28
  5 _Milan_                                                            37
  6 _The Monument_                                                     49
  7 _Success_                                                          60
  8 _The French_                                                       73
  9 _Cesare Borgia_                                                    86
  10 _Shattered Hopes_                                                 98
  11 _The Return to Milan_                                            114
  12 _Rome_                                                           129
  13 _The Last Years_                                                 147
  14 _Mankind’s Debt to Leonardo_                                     159
    _Significant Dates in Leonardo’s Life_                            162
    _Index_                                                           164



                                   1
                              _The Shield_


Dusk was beginning to gather in the valley at the foot of Monte Albano
as young Leonardo turned toward home. Stopping by a rushing stream to
wash the dust of the day’s explorations from his face, he laid aside his
cap and his leather pouch and plunged his hands into the cold mountain
water. He felt the force of the current and watched the whirl and flow
of bubbles around his bare arms. There was the same feeling, he thought,
to the flow of air he had experienced blowing around the rocky crags of
the mountains.

This evening, however, there was no time to sit awhile and think. He was
in a hurry to get home. Hastily scooping the water in his cupped palms,
he splashed it over his head and face, then shaking the water from his
hair he rose and picked up his cap. He took a satisfied look in his
pouch, slung it over his shoulder and headed down the stony trail to the
village of Vinci.

Vinci was a small hill town situated on a spur of Monte Albano. Its
castle and the bell tower above the houses seemed like sentinels
guarding the slopes of vineyards and olive groves spreading down into
the valley.

Leonardo da Vinci, which means “Leonardo from the town of Vinci,”
thought about his home. He knew that he had been born in Anchiano, near
Vinci, on April 15 of the year 1452, to a peasant girl named Caterina.
At the age of five, he had been sent for by his natural father, Piero da
Vinci, to come and live at his family’s house in Vinci, a comfortable
and roomy place with a spacious garden. Piero, five years before, had
married Albiera di Giovanni Amadori, a girl of sixteen. They had had no
children of their own, and Leonardo was welcomed into the home with
affection by his young stepmother.

When Leonardo was about eleven, young Albiera died, leaving a darkened
and saddened house. Two years later his father married another girl by
the name of Francesca Lanfredini. Although laughter and song soon
replaced the grief, Leonardo never forgot the love of his first
stepmother.

Also in the house lived Antonio, his grandfather, who was eighty-five,
his grandmother, his uncle Allessandro Amadori and family, and, best of
all, his uncle Francesco. The da Vincis, who could trace their
beginnings in the town back to the thirteenth century, had always been
respected lawyers and landowners. Because Uncle Francesco was neither a
lawyer nor a great landowner, the people of the town said he did
nothing; but he tended the family vineyards, and, to the delight of
Leonardo, he raised his own silkworms.

As Leonardo entered the main gate, he noticed that the oil lamps were
being lit above the stalls of the marketplace, and the lively confusion
of the last hours of business was in full swing. People nodded and
smiled to him, for as a boy of fifteen he was already a striking figure.
He was tall with long, auburn hair falling to his shoulders and his face
was so charming that it was frequently compared to those of the angels
painted in the chapels of the church. The music of his lute, the sound
of his voice, and the gentleness of his person were such that all hearts
and doors were open to him.

Tonight, however, Leonardo avoided the usual invitations to stop and
chat. His father would be back from Florence; he had been going there
more and more frequently as his fame as a lawyer grew. Now Leonardo was
thinking that he had almost finished the assignment his father, half
jokingly, had given him many weeks ago—so many weeks ago that he was
sure his father had forgotten about it. At that time a peasant, whose
skill in providing fish and game for the table of Piero’s big household
was greatly appreciated, had asked a favor of him. This man had a round,
wooden shield cut from a fig tree and he had asked Piero to have a
design painted on it for him in Florence. Piero, who had noticed the
sketches his son was making of plants, rock formations, and scenes in
his wanderings about the countryside, decided to test his son’s ability
and gave the shield to the boy. In the secrecy of his room, into which
no one was allowed, Leonardo had smoothed and prepared the wood, and on
it he was painting a monster.

Scrambling over rocks, through streams, and into caves, Leonardo had
been in the habit of gathering all manner of creeping and crawling life.
Patiently he would bring these home in his leather pouch and carefully
study and draw them. Maggots, bats, butterflies, locusts, and snakes
added to the confusion of the boy’s already cluttered room. Everywhere
he went he collected the things that aroused his curiosity; and as a
result, his room was always filled with rocks, dried plants, flowers,
the skeletons of small animals—and his pages of notations and drawings.
Now Leonardo had combined the features of these small forms of life to
make a monster—emerging from a dark grotto and breathing fire and
smoke—a thing more terrifying than if done from imagination, for each
feature was a duplicate of a reality in nature.

Unobserved, Leonardo reached the privacy of his room and emptied this
day’s collection on a table beside the shield. He lit a candle and
examined his catch—a lizard and a large grasshopper. These would
complete his picture; and, the most extraordinary find of the day—a
fossil seashell found high on the slopes of a mountain! How did it get
there? Was it a result of the flood about which his religion had taught
him? Had an immense wave deposited this ancient sea-life high on the
Albano mountains? Looking more closely he saw that it was a type of
sea-snail and in almost perfect preservation. This he would have to
think about and examine later.

Now, however, the picture must be completed, for he hoped to surprise
his father in the morning. But just then, Leonardo heard the family
stirring below and his father calling him to dinner. Reluctantly he left
his table, made himself presentable and went downstairs.

“Ah, Leonardo,” his father said when he appeared in the family dining
room. “I saw Benedetto dell’Abbaco on the way in town and he tells me
you haven’t been to school as often as you should—is that true?”

“Yes, Papa—but I’m not doing badly.”

“Signor Benedetto might agree, at least in your mathematics. He tells me
you ask him questions that often make him stop and think. But Leonardo,
you have other subjects—Latin, reading, and writing—as well as
arithmetic. You mustn’t neglect the others, my boy. But come—let us
eat.”

Together they sat down with the rest of the family—a large, prosperous,
and happy gathering. When dinner was over Leonardo made hurried excuses
to all the family, protesting that he was too tired to sing, and escaped
back into his room. For a long time he worked, unaware that the house
was growing quieter. Finally he laid down his brushes and his maul
stick, pushed his chair back and smiled a triumphant smile. The shield
was finished. Tomorrow he would ask his father in to look at it.

Conscious now that everybody had gone to bed, Leonardo blew out his
candle and opened the shutters. The night sky was a panoply of stars and
only here and there was the dark loneliness of the valley relieved by
pinpoints of light. Leonardo leaned his head against the window frame
and stared at the blue infinity above him. What exactly were the stars?
Did all of them move around the earth? What was the haze that obscured
the horizon ever so faintly? What was that sea-snail doing in the
mountains? Why? How?

The next morning Leonardo found his father and Uncle Francesco in the
garden deep in conversation about their vineyards and olive groves.

“Papa, I have a surprise for you up in my room—can you come now?”

“Yes, Leonardo. What is it you have found now—not a better way to raise
my grapes, I’ll wager!”

The elder da Vinci put his arm around the boy’s shoulder and went with
him up to the door of his room.

“Wait here, Papa, until I say to come in.”

Leonardo unlocked his door, lifted the cloth from the shield standing on
the easel and opened the shutter just a trifle so that a soft light
filled the room.

“Papa—you can come in now.”

Piero entered—he had long forgotten the round piece of wood—and suddenly
he froze in the middle of the room.

“Have mercy on me!” he said when he saw the horrible fire-breathing
creature. In the dimness of the room, the monster and the murky cave
from which it was emerging were terribly real. Piero actually started to
back out of the room in fright, when Leonardo laid a hand on his
shoulder.

“Papa, this work has served its purpose; take it away, then, for it has
produced the intended effect.”

The shield was the talk of the house; it was set up and marveled at. As
for Piero, he resolved to take it with him to Florence secretly and sell
it, giving his peasant friend some cheap substitute that he would buy in
the marketplace.

So, a few days later, Leonardo’s father saddled his horse and had the
shield wrapped and packed in his saddlebag. Also, unknown to his son, he
took some of the boy’s drawings. Piero had now realized that Leonardo
might have a rare talent. Moreover, he was planning to move to Florence
with his family so that he could be nearer to the Badia, or the law
offices of the city, for whom he had been frequently employed. There,
thought Piero, Leonardo’s talent could be developed under the best of
teachers.

It was many days before Leonardo’s father returned; when he did, he
gathered his family together and it was obvious to all that he had
exciting news. First, Piero announced that he and Francesca would move
to Florence since he and a law partner were now engaged in securing
office space from the Badia. It was a handsome office centrally located
opposite the palace of the _Podestà_, or chief magistrate.

Then, turning to Leonardo, he said: “I have shown some of your drawings
to Master Andrea del Verrochio and his enthusiasm for your skill has
decided me to place you in his studio as an apprentice. What do you
think of that?”

Leonardo was stunned. Verrochio, the great artist and sculptor!
Florence! The city-state whose power and influence had spread far beyond
her own walls. Now he would study in earnest; now he would find the
answers to his never-ending questions. He embraced his father and could
say nothing.



                                   2
                               _Florence_


The Italy of Medieval and Renaissance days was not a unified country as
it is today. It was, of course, part of the Holy Roman Empire, but the
main governing forces in the land were in the city-states, of which
Florence was one of the most powerful. A city-state was much more than a
city—it was almost a kingdom in itself. Each had its own army, and very
often there were large-scale wars between such city-states as Milan,
Naples, Rome, Venice—and of course Florence. The Italians of those days
considered themselves citizens—not of Italy as a whole—but of their
particular cities; people coming from other cities were looked upon as
“foreigners,” even though they looked the same, wore the same style of
clothing, and spoke the same language!

All the power, influence, and ideas of this period in history were
concentrated within the city-states. A man might be a very fine artist,
engineer, or philosopher, but unless he managed to bring his work to the
attention of the ruler of one of the cities, he was likely to remain in
obscurity. Thus it was that Piero da Vinci, knowing that his son would
have to have a powerful patron if he was to succeed at all, brought
Leonardo to Florence.

In 1467, when the da Vinci family entered Florence, the city had been
under the rule of the Medici family for some thirty-three years. As it
was in most of these city-states, the head of the ruling family—at this
time Piero de’ Medici—was in charge of the government of Florence and
the surrounding countryside. But Piero was fifty-one years old and
ailing, and he had only two years of life left at the time of Leonardo’s
arrival.


None of this was in Leonardo’s mind as he rode with his father through
one of the great, guarded gates of the city. He was thinking, not of
politics, but of the fabulous sights that awaited him in this rich
center of commerce and activity.

The narrow streets of the city were so crowded that is was necessary for
the da Vinci family, together with their servants and the donkeys laden
with household effects, to go single file. Leonardo rode behind his
father, shouting questions, and, at the same time, turning his head from
side to side so as not to miss a thing. Brought up in the solitude of
mountains and valleys, and accustomed to the quiet life of a village,
the boy of fifteen was overwhelmed with the excitement of the city.

    [Illustration: _Leonardo rode behind his father, turning his head
    from side to side so as not to miss a thing._]

The party was now making its way past the booths of hundreds of shops,
past magnificent palaces built by wealthy merchants, and across squares
filled with the produce from hundreds of farms. Every now and then,
Leonardo caught a glimpse of the cathedral dome, one of the
architectural marvels of its day. He had seen the cathedral with its
bell tower and also the towering spire of the Palazzo della
Signoria—which means the Palace of the Lords—from a hill as they
approached the city. This palace still stands and today it is called the
Palazzo Vecchio or Old Palace. But now these sights were lost to view in
the midst of the narrow streets, other churches, flags, and the lines of
washing that seemed to hang everywhere. Frequently, Piero’s party was
pressed against a wall as a procession shoved its way through a street.
Sometimes it was by armed horsemen escorting a rich banker to some
appointment; other times it was a file of cowled monks observing some
saint’s day and carrying huge wax candles before them.

After they had crossed the magnificent square of the Signoria, in front
of the Palace of the same name, Piero leaned down from his horse and
asked a blacksmith where Verrochio’s studio might be. The man shouted
above the din of clanging hammers:

“Everybody knows that shop, Signor—it’s down that street and to the
right! You can’t miss it—ask anybody!”

The man was right, for the workshop of Verrochio was not hard to find.
Verrochio was considered one of Florence’s finest artists and everybody
knew of him. He was a short, broad-shouldered man of thirty-two with a
round face, shrewd eyes, a thin mouth and dark curly hair that reached
almost to his shoulders. In his workshop were two other
apprentices—young Pietro Perugino, who was six years older than
Leonardo, and Lorenzo di Credi, a boy of eight. They all lived in the
house together and, after Leonardo was shown where he would sleep and
had put away the few things he had brought with him from Vinci, he was
taken to the place where he would work.

Verrochio, whose real name was Andrea di Michele di Francesco de’ Cioni,
had taken the name of his teacher, a renowned goldsmith, as was the
custom in the shops at that time. Verrochio himself was a skilled
goldsmith. But to be an artist and to have your own workshop in the year
1467 meant being a specialist in many things. Into Verrochio’s place
came a great variety of artistic work—painting pictures, sculpting and
architecture, goldsmithing, designing and making armor, creating
decorated furniture, designing mechanical toys, and even preparing stage
scenery.

Verrochio, of course, would attend to the greater creative tasks, while
his apprentices did the chores of grinding colors, preparing panels for
painting, making armatures for his sculpture, hewing to size the marble
for a statue, preparing molds for casting, building models for a new
palace or church—in fact, all the countless number of preparations to
the finished work. Sometimes, if an apprentice showed extraordinary
talent, he would be allowed to work on the finished painting or assist
with the final strokes of the chisel. Verrochio was a busy man and a
successful artisan. To further his own ambitions, he was now absorbed in
the perfecting of mathematical perspective and the study of geometry.

The curious Leonardo had come to the right man. In Verrochio’s workshop,
where so many crafts were learned at the same time, his powers of
observation were able to develop; his hunger to know about mathematics
was fed. In Verrochio, Leonardo found a teacher who would encourage
these investigations and urge him to study a wide variety of subjects.
Leonardo now felt his lack of a fuller education. He started to borrow
mathematics textbooks and to seek out men who could teach him what he
needed to know. After each day’s work was over, Leonardo would continue
on into the night, catching up on his neglected studies and discovering
for himself new areas of thought such as anatomy, movement and weight,
botany, and another subject which was to occupy much of his later
years—_hydraulics_, or the useful application of water power.

In these early years, Leonardo commenced his famous _Notes_. He had
developed his own “secret” writing in his childhood at Vinci. These
notes—consisting of observations, proportions, and reminders to
himself—were inscribed on his drawings. They were, however, unreadable
to the eye—until held up to a mirror. Leonardo was lefthanded and could
write fluently in this strange manner. It could have been for many
reasons that he did so—perhaps from a natural desire for secrecy,
perhaps for reasons of safety from possible enemies. In those days,
plots and counterplots of all sorts were commonplace—a rumor or a
whisper in the right ear could destroy a reputation or financially ruin
a career.

Leonardo was popular in Florence. He traveled with the young men of the
town, and his handsome appearance and enormous strength (he could bend a
horseshoe in his hands) made him a welcome figure in many houses. He
continued to play the lute and the lyre. He wrote poetry, composed his
own music, and sang with a pleasing voice. His blue eyes were kind and
his manner gentle. He always avoided arguments and competition when he
could. When he walked through the marketplace and came upon the caged
birds, he would buy them—just to set them free. Indeed, his love of
animals had become so great that he no longer ate meat.

During these years in Verrochio’s service, Leonardo grew in stature as
an artist and rapidly developed into a scientist of promise. He amazed
his master when he painted an angel in an altarpiece that had been
assigned to Verrochio. He painted it in the new oil colors recently
acquired from the Flemish painters. So astounded was Verrochio with its
grace that the master vowed he would never lift a brush again if a “mere
child” could so surpass him. In this picture there is a tuft of grass
beside a kneeling figure, also painted by Leonardo, which indicates by
its careful attention to detail the amount of research he did before
committing it to canvas. In other paintings he made beautiful drawings
of a lily and studies of animals and crabs, giving a hint of what was to
come. For, in these preparatory works, Leonardo could not be satisfied
until he had thoroughly studied the characteristics of plants and
animals in general. Later in life, he was to become more and more
absorbed in these researches until they occupied the greater part of his
time.

In 1469, when Leonardo had been in Florence only two short years, Piero
de’ Medici died and was succeeded by his son, the mighty Lorenzo de’
Medici—or Lorenzo the Magnificent, as he was often called. Now the city
of Florence felt itself under the control of a man who really knew how
to use power. Lorenzo was Florence; nothing happened without his making
it happen, and he became one of the most prominent patrons of art and
scholarship in all of Italy. If Leonardo was to make any headway in
Florence, he would have to make himself noticed by this new Medici
ruler.

But Leonardo was not yet worrying about how to make himself a success. A
young man of seventeen and still an apprentice of Verrochio, Leonardo
continued to meet new friends with new ideas. It was at about this time
that he met Benedetto Aritmetico, a prominent scholar and mathematician.
It is probable that this man drew Leonardo’s attention to the practical
needs of industry and commerce so that some of Leonardo’s energy was
directed toward the study and improvement of existing machinery and the
invention of labor-saving devices. At any rate, during these months
Leonardo was walking the streets of Florence, wandering into shops and
mills, making careful observations of all the various methods of
manufacturing. The more he saw, the more he thought to himself that one
man could do the work of many—if only he had the proper machine. He even
made drawings of laborers with picks and shovels to see if he could
determine by mathematics better ways to swing and hold the tools.

In addition, the particular problems in the engagement of joints
fascinated Leonardo, leading him on to the study of more general
problems such as the transmission of power by gears and the strength of
materials. He also spent long hours studying geometrical theories and
reading Greek and Latin classical works. Laboriously, he translated
these into his own formulas and made comments about them in his
notebooks. He attended the lectures of John Argyropoulos, a Greek, who
talked of the Aristotelian theories of natural history, and who had
translated Aristotle’s _Physics_.

The study of physics opened to Leonardo a whole new world of ideas. He
experimented with cogwheels, and with the improvement of ways to lift
weights. He became fascinated with the then-known laws of friction and
built a bench upon which he tested various devices for the overcoming of
frictional drag; he also tested the natural power of one body to set
another in motion. This bench with its rollers and weights was similar
in principle to the one used by the French physicist A. C. Coulomb
almost three centuries later. Leonardo was indeed growing into a man of
genius. Now everything from the stars to the flight of an insect
occupied his thoughts.

At the same time, he continued his studies of drawing and painting.
Frequently he was seen in Florence following someone whose face had
interested him—sometimes for the better part of the day—and then at
night he would fill a page with sketches of this same person from
memory.

By developing his powers of observation in this way Leonardo came to
rely more upon his own experiences and less upon what he was told or
what he read. This brought him into frequent conflict with the
astrologers, the alchemists and even the Church. The astrologers were
men who told fortunes by the movements of the stars. The alchemists,
with their knowledge of chemistry, pretended to be able to talk with
ghosts and to tell the future. These men Leonardo held in contempt.
Although he was a devoutly religious man, Leonardo objected to many
attitudes of the Church which he considered outmoded and which stood in
the way of scientific progress; because of these objections, he was
frequently called a pagan.

In this same year of 1469, Leonardo met the aging Paolo del Pozzo
Toscanelli. Toscanelli was a famous physician, philosopher and
mathematician who, just the previous year, had marked off on the
cathedral floor the famous meridian line for determining the dates of
the various Church holidays. The old man and the boy became not only the
famous teacher and ardent pupil, but close friends.

One evening at Toscanelli’s house, the old man showed young Leonardo a
globe of the world. Much of it was marked “unknown,” but Toscanelli had
filled in some areas from his own careful calculations and from the
stories told him by sailors and travelers. Visions of distant lands,
remote mountain ranges and vast oceans filled Leonardo’s imagination as
Toscanelli spoke. Then Toscanelli tapped the globe to the westward of
Spain, saying:

“Here will be found a quicker route to India than the world has ever
known before.” Then, turning to Leonardo he murmured, “You will see it
happen, my boy, in your lifetime.”

One by one, Leonardo’s childhood questions were being answered.
Toscanelli told him much about the stars, the fossils of creatures long
disappeared from the world, and how he believed the earth’s early
formation took place. He also taught the boy the art of drawing a map.
Not only did Toscanelli greatly influence Leonardo, but the course of
history as well. Ten years after Toscanelli had died, Christopher
Columbus, struggling westward over the Atlantic Ocean, was using a map
that old Toscanelli had sent him, carefully notated with all his
accumulated wisdom.

Leonardo, in keeping with his own philosophy, tested all this knowledge
with experiments of his own. Because astronomical instruments were rare,
crude, and costly, Leonardo borrowed them where he could and later set
about making his own. He went on to experiment with time measurements,
devising the first example of the application of a pendulum to regulate
a clock; by means of two springs, it measured the minutes as well as the
hours. So for the next three years Leonardo worked in Verrochio’s studio
and continued his studies and experiments.

In 1472 Leonardo’s name was inscribed in the Red Book of the Painters of
Florence, which was the official _guild_, or artists’ union of that
time. But he was so poor that he couldn’t afford the dues and hardly had
the money for the necessary candles to be burnt before St. Luke, the
patron saint of all painters. Although his father now had a spacious
apartment in a house on one of the main squares of Florence, Leonardo
continued to live with Verrochio. In fact, he stayed on past his formal
training period for about four more years, grateful to the kindly man
for the food and bed he offered.



                                   3
                         _A Studio of His Own_


On Sunday, April 26, 1478, the bells of the cathedral were ringing
loudly over Florence, almost drowning out the noise of the crowds in the
street. Shutters were being thrown open and people were shouting excited
questions at each other. Distantly at first, but growing in volume, was
another sound—an ugly one—the sound of an approaching, angry mob.
Leonardo, holding a roll of drawings closer under his arm, stopped and
listened.

Suddenly the questioning voices stopped. The bells continued ringing and
now the angry shouts of the mob could be heard.

“Lorenzo is dead! Giuliano is dead! Death to traitors! Pazzi! Pazzi!”

“On to the Palace of the Signoria! They’ve captured the Archbishop! He’s
a prisoner there!”

“Get a ram and we’ll break the door down!”

The people in the street were caught up in the surging mass. Already
soldiers of the Medici were spreading out through the city. Cobblestones
were ripped from the street, and swords, knives, and clubs were being
brandished in the air.

Leonardo, backed against a wall of a house, was soon left in an almost
deserted street. Still holding the drawings, he made his way carefully
back to his studio.

As it turned out, Lorenzo was not dead at all.

It was on this Sunday that the Pazzi conspiracy had broken out in
Florence. In the cathedral, the ailing Giuliano de’ Medici, brother of
Lorenzo, was killed by assassins. Lorenzo himself escaped with only a
scratched arm. The Pazzi family were rival bankers of the Medicis and
had joined in this plot with Girolamo Riario, a relative of Pope Sixtus
IV, and Francesco Salviati, a long-time enemy of Lorenzo. A hired
professional thug completed the members of the conspiracy.

Girolamo Riario hated the Medicis because they refused him money for his
own ambitions, and the Pope opposed Lorenzo because Lorenzo was
supporting raids against papal territory. As for Archbishop Salviati, he
had for years nursed a personal hatred for Lorenzo.

    [Illustration: _Leonardo, backed against a wall, was soon left in an
    almost deserted street._]

When the assassination attempt failed, the Archbishop and Francesco de’
Pazzi fled to the Palace of the Signoria for protection. However, the
members of the Council of Florence, who were meeting, then became
suspicious and bolted the doors after them. Both men were later killed
by the Medici followers and their bodies were hung from the barred
windows of the Palace. In the terror of the days afterward, eighty
victims lost their lives. The Pazzi conspiracy also had an effect on
Leonardo’s future, as we shall see later on.

Leonardo had been on his way to the Palace that morning. He had been
given his first painting assignment, or commission, the previous
January. This was to paint an altarpiece for the chapel of San Bernardo
in the Palace, and just the month before he had received the sum of
twenty-five florins as a partial payment.

Some time before January of 1478, Leonardo had left Verrochio and had
found a place of his own. The commission had come to Leonardo through
the influence of his father, who was now one of the leading notaries, or
lawyers, of the city. Though still poor, Leonardo could now devote this
new independence to his widening fields of study.

Leonardo’s studio was like his childhood room in one respect—it was
still filled with all the different things that had aroused his
curiosity. Books were everywhere—on his tables and shelves and piled on
the floor—books by Ptolemy, Pliny, and Strabo on geography and natural
history, by Aristotle on physics, even one by Guido, a tenth-century
monk, who has been called the father of modern music. In addition, there
were books on arithmetic, agriculture, geometry, grammar, philosophy,
fables, poetry and even one containing jokes. A map of the world hung on
the wall, together with his drawings; and, scattered throughout the
whole studio were the plants, fossils, rocks and animal skeletons he was
still collecting from his trips into the country.

There was also a huge table extending down the middle of Leonardo’s
studio upon which were many drawings and instruments for working
geometrical problems. His easel near the window supported a painting—a
study for his commission in the Palazzo. And on his desk was a confusion
of papers containing notes all written in his “secret” writing.

At twenty-six Leonardo was deep in the study of mechanical law,
geometry, and botany. For example, he had observed the rings in trees
and their relationship to the age of the trees. In mechanics, he was
absorbed in drawing models of a “variable speed drive.” By meshing three
cogged wheels of different diameters to a common lantern wheel, Leonardo
saw that different speeds of rotation could be obtained at the same
time. This same principle is used in the gear shift of modern
automobiles. About mechanics Leonardo wrote that it was “the paradise of
the mathematical sciences because by means of it one comes to the fruit
of mathematics.”

Now, too, he was starting to write about his observations on the flight
of birds, the formations of clouds and the behavior of smoke in the air.
He compared the flying of birds to the swimming of fish in the sea, and
the flow of air to the flow of water. Two hundred years before Newton,
Leonardo would define the principles of aerodynamic reciprocity, as
contained in Newton’s Third Law of Motion.

At this time, Leonardo had an idea for making the Arno river navigable
all the way from Florence to Pisa by the addition of canals, thus giving
Florence an outlet to the sea. He also had thoughts for the improvement
of irrigation in order to make use of land that did not have enough
water. Nothing that Leonardo saw in his day’s activities was too small
to pass unnoticed and unquestioned. The flight of a butterfly, the
stratification of rock in a cliffside, the shape of a mighty cumulus
cloud, the turning of a carriage wheel on a bumpy road, the play of
muscles in a farmer’s back, the curling of water around a rock in a
stream—all of these aroused Leonardo’s curiosity. Continually, he
studied these things and painstakingly drew them and wrote about them in
his notebooks.


Unfortunately, Leonardo’s painting commission for the Palace of the
Signoria was never completed. By the end of the year 1478, the Pope,
angered by the killing of the Archbishop during the Pazzi conspiracy,
had declared war on the Republic of Florence. Ferdinand, the King of
Naples, was persuaded to help in this war against Florence and the
Medicis. As the papal forces were approaching the fortresses on the
Florentine hills, the Council of Florence discontinued Leonardo’s
commission in order to conserve money for the defense of the city.

Disappointed though he was, Leonardo did not allow this setback to
discourage him. From a page of drawings in the Uffizi Gallery of
Florence on which are sketched various arms and war materials, we learn
that he turned from his artistic to his mechanical skills and began
designing engines of war. Besides being a Florentine concerned with the
defense of his city, Leonardo was eager to gain an appointment with
Lorenzo as military engineer to make up for the painting commission he
had just lost. Also, as the fifteenth century was a turning point in the
methods of waging war, Leonardo was attracted to all the mechanical
possibilities of the new artillery. Before then soldiers had used
spears, bows and arrows, and stone-throwing catapults, among other
primitive methods. One of Leonardo’s designs included a light cannon
whose barrel could be raised or lowered to proper elevation by means of
a hand-cranked screw and whose horizontal direction could be determined
by a maneuverable cradle.

The military appointment that Leonardo hoped for didn’t come.
Unfortunately for the Medicis, the war with the papal forces was being
lost. One by one, the fortresses under siege surrendered; more and more
of the Florentine troops were fleeing.

Leonardo continued the work on his military machines for, although he
was having some success painting Madonnas for private homes and had even
received a commission from the King of Portugal for a tapestry design,
he still wanted official recognition for his inventions from Lorenzo de’
Medici.

During these weeks late in the year of 1479, Leonardo conceived many
ingenious devices to wage war. Besides the small artillery piece, he
designed a _bombard_, or rock-throwing cannon, which did not recoil when
it was fired. This was followed by a light gun arranged in three tiers
of barrels, mounted so that while one tier was fired, the second was
being loaded and the third was cooling (a forerunner of the modern
machine gun). Another was a device to repel enemy ladders. It consisted
of a horizontal beam laid parallel to the top of a fortress wall; the
beam could be pushed outward by one man or several men using a system of
pulleys.

    [Illustration: _Leonardo’s design for a machine gun. It had
    thirty-three barrels in three banks of eleven each. While one bank
    was fired, one cooled and the other was reloaded._]

Unfortunately for Leonardo, just as he was ready to show these
inventions to Lorenzo de’ Medici, the last fortress outside Florence
surrendered and a three-month truce followed. Lorenzo himself went to
Naples and persuaded King Ferdinand to withdraw from the war. By 1480,
peace returned once again to Florence.

As for the Medicis, military machines no longer interested them. Greatly
disappointed at not having his inventions used—or even looked
at—Leonardo began to search about for new fields of creative activity.



                                   4
                         _Years Of Frustration_


The old monk spread the papers out before him on the table.

“Master Leonardo,” he said, “these are the terms of the commission. We
at the monastery wish to have an altarpiece painted for our chapel. Your
father has recommended you, and, as you know, he is our lawyer. Of
course your reputation has already reached our ears, and we are
satisfied in our choice.”

The year was 1480. The monk represented the monastery of San Donato a
Scopeto near the Porta Romana, just outside Florence. Leonardo shook his
head slowly at the terms of the commission. The painting had to be
completed in thirty months at the most. Moreover, he must pay for his
own colors and even—Leonardo looked up as if to protest but resumed
reading—even pay for any gold or gold leaf he might use. Nevertheless,
it was an opportunity, and Leonardo needed work. Since the papal war had
ended, he had not received any commissions—and his skill at military
engineering was still too unknown to have won him recognition.

Although Lorenzo de’ Medici was a great supporter of the arts and
sciences, he had not granted Leonardo any of his patronage. In Lorenzo’s
court were many men with much book-learning but little talent. They
guarded their positions jealously and kept the way to Lorenzo barred to
any applicant whom they did not like. Of them, Leonardo wrote in his
notes: “They strut about puffed up and pompous, decked out and adorned,
not with their own labors, but by those of others, and they will not
even allow me my own. And if they despise me who am an inventor, how
much more blame be given to themselves, who are not inventors but
trumpeters and reciters of the work of others?”

In accepting the commission to paint the altarpiece, Leonardo hoped to
attract attention to himself. Perhaps then Lorenzo might welcome him to
his court and grant him patronage. So, with his usual thoroughness,
Leonardo set about the task of preparing an Adoration of the Magi—a
favorite subject of that time. This was to be a picture of the Holy
Family surrounded by the three wise men from the East, shepherds and
animals, old and young, rich and poor, paying their adoration to the
Christ child.

Since he wanted his subjects perfect in every detail, Leonardo set about
drawing countless youths, old men, sheep, oxen, horses, and donkeys. In
a separate drawing for the background, he worked out with mathematical
mastery the problems of perspective, that is, drawing objects to make
them appear three-dimensional and either close or far away in space. In
addition, he made studies for the composition of the whole
picture—studies in which his knowledge of geometry was used to heighten
the excitement of this great religious subject.

    [Illustration: _Leonardo’s hygrometer._]

Among these sketches that Leonardo made for his “Adoration of the Magi”
is a page on which appears an inspiration for one of his greatest
masterpieces—a drawing of the “Last Supper.” And on this same page is
another drawing—one of a hygrometer. A hygrometer is an instrument for
measuring the amount of moisture in the air. Leonardo’s design consists
of a simple, graded disk with a balanced pointer, weighted at one end
with sand and at the other with a sponge or some salt. As the sponge or
salt absorbed the moisture in the air, the added weight was indicated on
the graded disk, thus measuring the amount of humidity.

Leonardo’s researches for the altar painting took him almost a year.
Although the monks began to grumble at his slowness, Leonardo would not
be hurried. He was determined to produce a painting that was perfect in
all respects. To quiet their impatience Leonardo did odd jobs for them
in the cloister. He repainted their old clock and for this extra work
they advanced him some much-needed money. In March of 1481 Leonardo was
ready to begin the actual drawing for the altarpiece. As he progressed
with the composition, the monks crowded around with exclamations of
delight. So different was it from all the other Adoration pictures they
had ever seen, that the monks sent Leonardo some sacks of corn as a
token of their appreciation.

One day, Leonardo was walking slowly toward the monastery over the Ponte
Vecchio—the Old Bridge—across the Arno River. He made his way slowly up
the hill past the construction for the new Pitti Palace. The morning was
hot and the farmers moving into the city with their heavily laden carts
were short-tempered. Leonardo stood to one side as he watched a pair of
oxen straining to haul a wagon up a rise in the road. Their owner, his
shirt unbuttoned to the waist, was shouting angrily, lashing the animals
with his leather-thonged whip. It was a cruel sight and Leonardo turned
away. From some experiments he had been making, Leonardo realized that
the poor animals were struggling not only with the hill, but the drag of
friction on the creaking axle. This drag could be eased, he thought to
himself, by simply resting the axle in two sets of roller-bearings
attached to the bottom of the cart near each wheel. In his mind he
formed the plan for such a model as he made his way to the monastery.

The drawing of the altarpiece was nearing completion. The monks were
fascinated by the spectacle of the Adoration appearing before their
eyes. The soft, umber outlines deepened with gray, the ochre
highlighting the central figures charmed them and they sent another gift
to Leonardo’s house—a cask of Tuscan red wine.


As it turned out, Leonardo never finished this altarpiece. It is not
known why. But the drawing for it can be seen today in the Uffizi
Gallery in Florence just as Leonardo left it.

It is certain, however, that Leonardo was far from idle during this
time. He drew the design for eliminating the friction of a turning axle
by mounting the axle in roller-bearings. He experimented with, and
solved the problem of, transmitting motion to revolving machine parts by
friction—the possible forerunner of our modern friction clutch. Another
device, found in modern automobiles—the differential—was also drawn by
Leonardo. This idea provided for the difference in speed between the two
drive wheels when rounding a curve.

Leonardo also drew the first known plans for a self-propelled vehicle—an
“automobile.” It was designed to operate by a system of elastic springs
wound by hand by the person on the vehicle; the “car” was then supposed
to run the short distance allowed it by the unwinding of the springs.

In addition, Leonardo continued designing machines for both offensive
and defensive military action. One of these was a breech-loading cannon,
together with the first known projectiles that took into consideration
better penetration through the air and greater stability in their
trajectory. Indeed, these very much resembled present-day aerial bombs,
with pointed noses and stabilizing fins.

As the months passed, however, Leonardo began to feel that his time and
talents were being wasted in Florence. Although the monks and friends of
the monastery were pleased with the work he was doing, other artists
were being called to greater tasks in Rome. For example, Domenico di
Tommaso del Ghirlandaio, Sandro Botticelli, and even Leonardo’s fellow
student, Pietro Perugino, had left Florence to work in the chapel of
Pope Sixtus IV in Rome—known to us as the Sistine Chapel. Now, too, it
was becoming clear that Lorenzo and his court had no time for this
solitary genius whose ideas stretched beyond his age.

So Leonardo looked about him. He was thirty years old and the walls of
Florence seemed to bind his spirit. To what city could he go where his
talents would be put to fruitful use? Rome seemed to hold out no hope,
for no one had offered him a position there.

But Leonardo remembered that there had been a visitor to the Medicis
from another city in recent months. This man was Ludovico Sforza, the
ruling prince of Milan, the great city-state of the north. Ludovico, who
was also called “Il Moro” (the Moor) because of his dark complexion, was
seeking the friendship and alliance of the Medicis. He was fascinated
with the art and culture of Florence and sought to gather to his own
court of Milan as many artists, scientists, philosophers, and musicians
as he could.

Perhaps, thought Leonardo, his future lay in Milan. So he began
collecting his countless drawings, diagrams of machines and instruments
of war, his notes, his plans for canals and irrigation—even a drawing
for a monument that he knew Ludovico wanted to erect to his father—and
made a package of it to send to Ludovico. Then he sat down to write a
letter to that nobleman. In it he set forth in ten numbered paragraphs
his qualifications as military and naval engineer, architect, and
hydraulics expert. Almost as an afterthought to the tenth item, he
wrote: “I can carry out sculpture in marble, bronze, or clay, and also I
can do in painting whatever may be done, as well as any other, be he who
he may.”

When he had finished the letter, Leonardo took out a strange instrument.
It was a lyre of silver in the shape of a horse’s head. He had designed
it himself, and now with an air of peace, he commenced to play. Its rich
tone was sweet to hear and the music was his own composition.

Leonardo had also designed other instruments—lyres, lutes, viols, and a
kind of zither. He had perfected the single-stringed monochord of
Pythagoras, replacing the tablet of wood with thin strips of drum that
gave the instrument a low or high note according to the tightness of the
string. In addition, he introduced stops or small pistons in the holes
of wooden reed instruments; and, he had even invented a set of
mechanical chords by using a wheel of reeds which plucked a set of
strings as it was turned. His skill as a musician, composer, and singer
was well known among his friends and his bass voice had retained the
pureness of his boyhood.

As it happened, news of Leonardo’s silver lyre had reached Lorenzo de’
Medici. All Leonardo’s paintings, all his designs for cannons and
fortifications, all his inventions for commercial machinery had failed
to interest Lorenzo—yet this single musical oddity excited the ruler’s
curiosity. Leonardo was summoned to the Medici palace.

Lorenzo was enchanted both by the instrument and Leonardo’s musical
talent. When Leonardo had finished playing, Lorenzo, surrounded by
members of his court, applauded and said,

“It would please us if Master Leonardo da Vinci would present us with
this beautiful instrument so that we, in turn, could make a gift of it
to His Highness, Ludovico Sforza, of Milan.”

Leonardo bowed and replied,

“Your Grace’s request is my pleasure. Moreover, Sire, it would further
that pleasure to bear the gift myself to His Excellency in Milan.”

The idea delighted Lorenzo. He immediately directed that Leonardo be
given a letter to Ludovico and that every protection be given Leonardo
for his journey.

Leonardo, with the silver lyre and the letter of recommendation, hurried
home to make his final preparations. He called on a friend and pupil,
young Atalante Migliorotti, to accompany him.

Toward the end of 1482 or the beginning of 1483, with the letter to
Ludovico folded in a leather pouch, Leonardo and Atalante mounted their
horses and left Florence for the long journey to Milan.



                                   5
                                _Milan_


Milan at this time was one of the greatest and wealthiest city-states in
all Europe. Its battlements and the spires of its mighty cathedral rose
impressively from the lush plain of Lombardy. Towering over the city in
the distance were the snow-capped peaks of the Alps. Groves of mulberry
trees for the production of its famous silk industry and vast stretches
of rice paddies extended far into the surrounding countryside.

Leonardo and Atalante rode along the embankment of one of the many
canals. The sight of the city hastened their pace although the journey
had been a long one. Frequently on the trip Leonardo had stopped to make
notes. Riding over the mountains and ravines surrounding Florence he had
drawn some of the rushing streams and the stratifications of exposed
cliffs. And when they had descended to the plains he observed the
irrigation ditches and made notes on ways of improving the crude systems
of dams and waterwheels.

Leonardo was excited by this new city and by his prospects at the court
of Ludovico. On the way to his lodgings, he also noticed that Milan was
a great center of arms manufacture. Shop after shop displayed its wares
of swords, spears, shields, armor for man and horse, and signs
advertising foundries for the making of cannon. Perhaps here he might
find an outlet for his military inventions.

In the inn where he and Atalante stayed, Leonardo overheard the current
political rumors. All around him was talk of the war. Girolamo Riario
was again in the field, and Ludovico’s ally, Alfonso of Calabria, had
just been defeated by the Venetians in a bloody battle at Campo Morto.

Leonardo reread the letter he had written setting forth his own
accomplishments and decided that now was the time to present himself as
a military engineer. He would minimize the bronze monument, his music,
and his painting, and instead, he would stress his skills in the
inventions of war.

When Leonardo appeared before Ludovico, he was a handsome young man of
thirty-one. Tall and strong, he was dressed not according to fashion,
but simply—almost severely. His hair hung in curls on his shoulders and
his auburn mustache and neatly trimmed beard accented his ruddy
complexion and deep-set blue eyes. Indeed, he presented a striking
contrast to the nobleman seated before him. Il Moro, with his dark skin
and straight black hair, his richly embroidered doublet with its broad
sleeves and the heavy gold chains across his thick chest, was the exact
opposite of Leonardo.

Ludovico set aside Leonardo’s letter, rose from his chair, and walked to
the heavy table on which Leonardo had spread out his drawings.

Plans for all manner of war machines were there—those that Leonardo had
designed for Lorenzo de’ Medici without success, together with many new
additions. For example, there were plans for a self-propelled bomb with
flames to be shot out in all directions—a bomb that was later to be
called a “rotatory rocket” when it was actually invented in 1846.
Leonardo also explained to Ludovico his idea for “poison gas” bombs
containing sulfur: the fumes of these bombs would “produce stupor,” and
they could be used both on land and sea, together with masks to protect
those who were using them. Shrapnel shells, hand grenades, and javelins
that burst into flame when they struck their objectives—these and many
more were among his ideas.

But perhaps the most unusual to Ludovico’s eyes was the design for an
armored vehicle. It was shaped like a giant turtle, with overlapping
sheets of reinforced wood so that enemy shells would bounce off its
surface. The armor was pierced by loopholes for the breech-loading
cannon and there was an opening at the top for ventilation. Power for
the vehicle was supplied by eight men inside turning cranks which in
turn were cogged to other wheels, setting in motion the four drive
wheels. This of course was the forerunner of the tank and the armored
car used in modern warfare.

    [Illustration: _Forerunner of the tank or armored car, as conceived
    by Leonardo. Motion was supposed to be supplied by four cogged
    wheels turned by manpower. Sheets of reinforced wood were supposed
    to serve as “armor” against enemy projectiles._]

In addition, Leonardo laid before Ludovico all manner of cannons and
designs for tunneling under the enemy’s defenses. Actually, with respect
to warfare itself, Leonardo called it a most brutal “madness”; however,
he recognized the necessity of being prepared. In his notebook, he
wrote, “When besieged by ambitious tyrants I find a means of offense and
defense in order to preserve the chief gift of nature, which is
liberty.”

Ludovico was very much interested in the things Leonardo had showed him.
Although he was a man of limited imagination and was not able to grasp
the scope of Leonardo’s proposals, he was nevertheless involved in a
war. Since Ludovico’s aging military engineer was to be replaced,
Leonardo left the forbidding castle of the Sforzas with high hopes of
getting the position.

In the meantime, he was commissioned to paint the portrait of a young
girl from a noble family in Milan. At the same time, he began the bronze
equestrian statue of Ludovico’s father, Francesco Sforza. For this work,
he began an intensive study of horses. Since hunting was the popular
sport at the court of the Sforzas, Ludovico owned a stable of the finest
Arabian horses, and here Leonardo commenced his drawings. Again, his
research for a work of art led him beyond just making preparatory
sketches. His studies developed into notes, and his notes into a planned
book on the anatomy of the horse.

During these months of waiting for the appointment as military engineer,
Leonardo furthered his experiments with cannon. In the course of these
experiments, he came across a power that would later revolutionize all
industry—steam. He devised—although he attributed the original idea to
Archimedes—a water vessel connected to a copper tube which was heated by
a fire. The water when flowing into the red-hot tube changed into steam
and the pressure of the steam blew out a ball at the mouth of the tube
with great force. Leonardo experimented with steam in other ways. He
built an apparatus for measuring the transformation of water into vapor.
It consisted of a metal box in which was a thin animal bladder partly
filled with water. Resting on the top of the bladder was a flat lid
attached by a cord hung from two pulleys to a counterweight on the
outside. As the water was heated, the steam in the bladder pushed up the
lid. As the lid rose both the volume and the pressure could be measured.
There were distillation experiments with various condensers, one in
particular that anticipated the modern condenser of Leibig, introducing
double walls that formed a complete jacket for cooling with water in
continual circulation.

Not content with having an idle moment, Leonardo again turned to
searching out books that he had not read and trying to fill the gaps in
his education. He became especially interested in the German
philosopher, Cardinal Cusanus. Cusanus, like himself, had been
influenced by Toscanelli and was a man devoted to the natural sciences.
Leonardo also studied the philosophy of Aristotle and the writings of
St. Augustine. Throughout his life Leonardo believed in an active mind
for, as “iron rusts from disuse, stagnant water loses its purity and in
cold weather becomes frozen, even so does inaction sap the vigor of the
mind.”

Unfortunately, the post of military engineer went to a man named
Ambrogio Ferrari. The extent and variety of Leonardo’s proposals were
too great for Ludovico to trust. He did not believe that one man could
possibly bring all those ideas into being. Ferrari, on the other hand,
was a military engineer only, and a man who was content with the
customary methods of warfare. Furthermore, Ludovico had at last decided
that peaceful negotiations would gain him more than fighting. Thus
Leonardo’s chance of recognition was again postponed.

Meanwhile, the money that Leonardo had brought with him from Florence
was almost gone. He had been forced to move from his apartment to a
single room and now he was barely able to live from day to day. Although
the court of Ludovico Sforza was one of the richest in the world,
artists were frequently treated as servants; often they were the last to
be paid for their services. Also, Leonardo was a foreigner in the city,
which meant he was regarded with suspicion.

Because of these reasons, Leonardo finally decided to do what the
Milanese artists did—they banded together in groups sharing work and
costs. Leonardo had met a young artist of twenty-eight, Giovanni
Ambrogio de Predis, at the court of Ludovico. Ambrogio was court painter
to the Sforza family and had achieved some success. Ambrogio recognized
in the handsome stranger from Florence, however, the touch of genius,
and he realized that his own talents would be furthered by learning from
Leonardo. The two young men decided to pool their abilities. Ambrogio
offered both lodging and a studio; and, in association with his two
half-brothers, one a woodcarver, another a miniaturist, and his elder
brother, a minter of coins, they would not lack for commissions.

Commissions weren’t long in coming. On April 25, 1483, a contract was
signed between Bartolommeo degli Scarlione, a prior of the Fraternity of
the Immaculate Conception, and Ambrogio and Leonardo for an altarpiece.
The fee was two hundred ducats, with a promise of more if it were
delivered on time and was satisfactory to the Fraternity. Delivery date
was to be December 8, 1484. Ambrogio was to paint the altar wings and
Leonardo the center piece—a picture of the Blessed Virgin and Child.

But when the painting was finished, it was not according to the
instructions set forth in the contract. Leonardo had too independent a
mind to be bound by conformity. Nor was it completed on time. Indeed,
for twenty years the quarrel between the Fraternity and the painters
went on. After ten years, Ludovico was asked to intervene for the money
owed; after he failed, another ten years went by and the King of France
himself was finally asked to settle the dispute. Leonardo wanted his one
hundred ducats and the Fraternity offered twenty-five. Eventually, a
secret agreement was arrived at and the painting was restored to
Leonardo and Ambrogio. Leonardo’s painting, the masterpiece entitled the
“Virgin of the Rocks,” now hangs in the museum of the Louvre in Paris.

The day this contract was signed, Leonardo walked back through the city
to Ambrogio’s studio near the Ticino gate. He was low in spirits from
reading the petty instructions of the contract, and, in this mood, he
became aware of the city streets and crowds about him. The noise, the
confusion, the smells—yes, the smells were the worst. Garbage, filth,
and dust were in heaps where the last rainwater had left them and they
buzzed with flies.

Moreover the houses were jammed together and shopkeepers crowded their
wares to the edges of the streets, leaving just enough room for the
occasional horseman to get through. Latrines were only for the better
houses; here, the streets, alleys and even open doorways were toilets.
People flung their scraps out of the window and at night in the poorly
lit streets could be heard the scurrying of rats. Leonardo stopped,
thinking half aloud:

“Two levels. Streets running one above the other—one for pedestrians and
one for carts and horses. Yes, and cutting through the whole city a
system of canals to carry the city’s waste to a river or to the sea. Why
not even ten cities of, say, five thousand houses in each—say, no more
than thirty thousand people to a city?”

Intent now on his thoughts he hurried to his home, his mind busy with
his visions of new cities.


During the years 1484 and 1485 the bubonic plague swept Italy—the same
dreaded Black Death so prevalent in medieval times. Milan was one of the
cities most severely stricken. Every courtyard became a hospital and the
streets were deserted except for the rumbling carts picking up the dead.
On the roads from the city were lines of refugees fleeing to the
country. Surrounding cities that had not been infected manned their
fortress walls as in wartime to keep the fleeing populations out.

Ludovico at first tried to protect Milan from the spread of the disease;
then, frightened, he and his court fled. Even the ruler’s official
documents had to be “disinfected” by perfume and then held for a period
of time before he would allow them near him.

Leonardo, sensing opportunity, drew out his plans for his new cities.
Canals running through them were to be used for barges and the
underground conduits greatly resembled those of modern sewage systems.
Paths were to have gutters for the adequate drainage of the streets.
Public toilets were to be installed. Leonardo even had plans for the
control of smoke collecting over the city—by sending it up tall chimneys
where it was picked up by fans and driven away over the roofs. The
widths of the streets were to be in proportion to the heights of the
houses—light and air would circulate freely. Two levels would be
connected by graceful ramps—the lower level for the commercial traffic
and the upper level for the pedestrians. Where stairs were used they
were designed so one could ascend or descend without one person seeing
the other. Stables were devised so that animals were fed through
openings in their mangers and under these were tunnels of flowing water
for the removal of waste.

    [Illustration: _The results of the bubonic plague in Italy, 1484-85.
    Streets were deserted except for the carts picking up the dead._]

These sweeping plans Leonardo laid before Ludovico when the epidemic had
subsided. But Ludovico, once his fear was overcome, brushed them aside
as impossible dreams.

So Leonardo returned to the commission for the Fraternity and the
designs for the bronze monument of Francesco Sforza. These jobs kept
Leonardo from brooding about his rejections.

Often, too, Leonardo worked with Bernardino de Predis, the elder brother
of Ambrogio. Bernardino was a minter of coins. As Leonardo watched him
at the laborious task of first cutting disks from ingots and then
hammering the design into the hot metal, he suggested to Bernardino an
easier method, then used in Germany. This was to prepare smooth ribbons
of metal of the desired thickness and with a punch, impress the design
into the ribbon at the necessary intervals and then, punch out the coin.
Leonardo went on to improve this system by designing precise punches for
both faces of the coin. A single machine then cut out and stamped the
coins, using a falling weight raised by little winches. This machine was
later destined for the Vatican mint in Rome.

On March 26, 1485 an event occurred in Milan that was viewed with
mingled fear, superstition, curiosity and excitement. There was a total
eclipse of the sun. To some, coming as it did so soon after the plague,
it was a judgment of God; to others, it was regarded as an omen—a sign
for astrologers to use for predicting the future.

But to Leonardo the eclipse was a moment of great scientific importance.
At this time in history, the Ptolemaic, or geocentric theory of the
universe was the popular belief. This theory taught that the earth is
fixed and the sun and moon revolve around it. Leonardo himself had
believed this theory for a long time. As he grew older, however, he read
and heard discussions of the heliocentric theory. This theory proposed
that the sun is fixed and the earth and stars move around it. Now, as he
watched the eclipse, his doubts of the Ptolemaic concept were renewed
and he resolved to make experiments of his own. The new theory was so
daring for his times, however, that it would be many years before he
became convinced of its truth.

Later that night, deep in thought over the experience of the day, he
noted down his observations of the eclipse and his doubts of the
medieval concept of the heavens. The Church believed the earth was the
fixed center of the universe. Scholars and scientists supported the
belief of Aristotle in the four elements, earth, water, air, and
fire—but something was wrong. What were the planets—what was the moon?
He picked up his pen and on a clean sheet of paper he wrote, “Make
glasses in order to see the moon large.”



                                   6
                             _The Monument_


During this time, Leonardo had been struggling with the design for the
bronze equestrian statue. Drawing after drawing lay scattered on his
studio floor. Lately, however, a daring plan for this statue had come to
him. It was to be a huge bronze warrior, Francesco Sforza, mounted on a
rearing horse. Weighing perhaps a hundred thousand pounds, it was to be
cast in sections in five furnaces—a fitting monument to the power of the
Sforza family. But there still remained a big problem to be solved: how
could he balance the plunging horse and man on just the two rear legs of
the horse?

Meanwhile, Leonardo had another problem to work on—a wooden model of the
Milan cathedral. He had entered his name with the cathedral authorities
as a competitor in the design and construction of the cathedral’s dome.
Many architects had been brought in and had failed, partly because of
the antagonism of the Milanese workmen to foreign craftsmen, and partly
because the committee found it difficult to decide what designs it
liked. Leonardo had sent them a letter outlining his own recommendations
and had drawn many pages of possible plans. He put forward his knowledge
of various building materials, his understanding of classical
architecture, and his wish to keep his own ideas in harmony with the
Gothic tradition of the cathedral itself. Often he would make a point of
walking about the city, observing the different constructions under way
and drawing up plans to shorten the labor by mechanical means.

In July of 1487 Leonardo received a payment from the cathedral
authorities for the wooden model he had submitted. Still, however, no
final decision had been reached. Now, as Leonardo looked at the model in
his studio, he felt the urge to improve it further—to make it more
perfect. Yet he held his impatience in check and decided he would wait a
little longer. Instead, he decided to work on some of his ideas for
construction devices. He had already made many drawings, but they could
be improved, he thought, and he began to make calculations.

Among these notes and drawings was an improvement on a device for the
raising of columns. It was a mobile windlass with a transmission gear
for transporting and erecting columns and obelisks. Another device was
an earth drill resembling a modern corkscrew with double handle bars.
The upper bar, when turned, drilled the screw into the earth while the
lower bar—when turned the opposite way—carried the dirt up and out. Also
there was a double crane mounted on a circular trolley which carried the
dirt of excavation up and then the crane was moved around on its trolley
so the dirt could be unloaded in different directions.

Other labor-saving devices that Leonardo designed were an automatic pile
driver, the weight of which was raised by a winch and tripped
automatically at its height to fall on the piling; a lift for raising
iron bells to bell towers; and a machine for boring tree trunks to make
pipes for carrying water.

In the fall of 1488, Leonardo was interrupted by a summons from
Ludovico, who wanted him to design and build the decorations for the
forthcoming marriage of his nephew, young Duke Gian Galeazzo Sforza, to
Isabella of Aragon, granddaughter of the King of Naples. He worked on
this steadily until the wedding ceremony in February of the following
year. When the day arrived, the street from the cathedral to the grim
castle was trimmed with flags and banners of the two royal houses. The
inner courtyards of the castle were transformed into delicate arbors of
laurel boughs. Yet it was the evening’s reception and entertainment
which were to be the climax and to them Leonardo had brought all his
mechanical skill. However, the announcement of the death of the bride’s
mother cut short the celebration and, after the bride and groom had left
for Pavia, the wedding party soon dispersed. Disappointed that his
decorations had not been fully appreciated, Leonardo returned to his
studio and the problem of the monument.

He was still struggling with the problem of balancing the rearing horse.
And, indeed, a solution was soon found. By placing a fallen soldier with
his arm upraised in protection under the forefeet of the horse, Leonardo
could balance the enormous weight and provide for the proper casting of
the molten bronze.

Finally, Leonardo made a small wax model of the proposed statue and
showed it to Ludovico. The nobleman was impressed by its originality.
Most of the ideas contributed by other sculptors were mere variations of
what had already been done many times. Also, the other plans called for
bronze of not more than two thousand pounds, while Leonardo envisioned a
statue fifty times that size! Ludovico awarded the commission to
Leonardo.

Leonardo was to work on this commission for ten years and it was
destined never to be immortalized in bronze, for reasons that will be
explained later. His energies, as usual, were poured into many schemes.
Growing out of his work on the monument he planned one book on the
subject of casting in bronze and another on the anatomy of the horse.
But the one subject, which he began to study in this period and which
would occupy the remainder of his life, was the study of human anatomy.
So Leonardo, in the midst of all his other activities, wrote in his
notes, “On the second day of April 1489 the book entitled _Of the Human
Figure_.”

The sources of anatomical study up to Leonardo’s day had been the
Greeks—Hippocrates and Galen—and the Arab—Avicenna. Books on this
subject were few, and the anatomical diagrams were crude and inaccurate.
Galen, for example, had based his studies on the dissection of monkeys.
Renaissance anatomists had explained his errors by pointing out that man
had probably changed since Galen’s time. The Church had stepped in
during the fourteenth century with an edict that was interpreted as a
prohibition against dissection of the human body. In Italy, however,
there were some dissections. They could only use, for this purpose, the
bodies of criminals, slaves, and people of foreign birth. In Florence,
anatomy was studied by the artists, and Leonardo had undoubtedly watched
Pollaiuolo at work on a corpse that that artist had dissected.

In 1489 Leonardo, from the results of his own investigation, produced
drawings of the skull and backbone whose careful attention to detail
are—even today—classics in art and anatomy. With infinite patience and
with a saw of his own invention he had halved a skull and drew for the
first time with accuracy the curves of the frontal and sphenoid bones.
He drew the lachrymal (tear) canal, and he was the first to show the
cavity in the superior maxillary bone—not discovered again until 1651,
by Highmore—now named “the antrum of Highmore.” He was the first to
demonstrate the double curvature of the spine and its accompanying
vertebrae, the inclination of the sacrum, the shape of the rib cage, and
the true position of the pelvis. He planned a whole series of books that
would include from head to foot and from inside to outside every section
of the human apparatus.

Meanwhile he had been working on the monument, redesigning it to conform
to the practical needs of casting. Now it had reached an even grander
scale—a colossus that would require two hundred thousand pounds of
bronze! He recorded in his notes the very day that this work was
started, “On the twenty-third day of April 1490 I commenced this book
and recommenced the horse.” The “horse,” of course, was the monument and
“this book” referred to still another subject which had grown out of his
studies of anatomy and perspective.

The title of the proposed book was to be _Light and Shade_. It would
include the subject of optics or the mechanism of the eye, the problems
of reflection and refraction and it would lead him eventually to a
re-examination of his studies of the sun and moon.

In Leonardo’s day, and even for a long while afterwards, the popular
belief of vision was one that had originally been put forth by the
Platonic school and expanded by Euclid and Ptolemy. This belief was that
the eye sent forth rays that brought back the image to the soul.
Leonardo, in his younger days, had believed in the same theory. Not
content with what had been written on the subject, however, he began to
experiment for himself.

These experiments led him to an examination of the eye itself. He noted
the various parts of the eye—the optic foramen or opening, the pigment
layer, and the iris. These were already known by the Arabs. Leonardo
discovered, however, the crystalline area of the eye. He explained
binocular vision, or three-dimensional images, by correctly noting the
positions of the two eyes in the head. He described the variations in
the diameter of the pupil according to the surrounding light. Further
experiments with light brought him to the conclusion that light and
images are received by the eye. He took a piece of paper, for example,
and pierced it with a small hole. With this he looked at the source of
light. He noted the cone shape of the rays funneling into the tiny hole
and then when the paper was held next to a white wall he noted that the
rays spread out again. He established that light travels in straight
lines. He constructed the first “camera obscura”—a box with a small hole
in it. Inside the box an object was placed near the hole and behind that
a lighted candle. When the box was closed the image of the object was
cast on the wall. Leonardo was already acquainted with lenses, and he
placed a magnifying lens over the hole to create an enlarged image.

    [Illustration: _Leonardo’s “camera obscura” which he used for
    projecting an image of an object on a wall or screen._]

He also demonstrated various laws relative to optical illusion, such as
irradiation—when a metal rod is made red-hot at one end, that end seems
thicker than the other. A brightly lit object seems larger than one
exactly like it that is dimly lit; a dark object placed against a light
background seems smaller than it is; a light object seems larger than
its real size when placed against a dark background; and the illusion of
a light swung in a circle appears as a complete circle of light.

Many years before Newton, Leonardo described the experiment of breaking
up a ray of white light into the solar spectrum. Also he compared two
sources of light and measured their intensity by the depth of their
shadows accompanied by a drawing that was the forerunner of Rumford’s
photometer three centuries later! He stated the law of reflection—that
is, that the angle of reflection is always equal to the angle of
incidence.


About this time Leonardo left the studio of Ambrogio de Predis and moved
into the Sforza Castle. Ludovico had put at his disposal a studio in the
Corte Vecchia and the use of a room in one of the towers—which Leonardo
always kept locked. To his growing list of work, Leonardo now had to add
the preparations for the delayed wedding reception of Ludovico’s nephew,
Gian Galeazzo Sforza.

On a cold winter evening of January 1490 the guests assembled again.
Silks, satins and gold brocade, diamonds, rubies and pearls glittered in
the brilliant lights. Princes of the Church mingled with ambassadors of
foreign lands. Music and perfume filled the air and as the party quieted
down the entertainment began. There were dances in gay costumes. Poetry
was recited that flattered the bride and groom. There were allegorical
processions. The jokes and antics of the court jester made the audience
laugh.

Then, at midnight, the curtain that hung from wall to wall at the end of
the ballroom was raised. Applause and cries of delight greeted the
spectacle. The rising curtain revealed a room in which there was a
hemisphere surrounded by the signs of the zodiac and the planets. While
the planets in their niches flickered with concealed lights and the
signs of the zodiac glowed, lines were spoken in honor of the house of
Sforza to the accompaniment of a choir. The ancient gods swept down from
the heavens, and the Virtues and Graces moved across the scene with
nymphs waving lanterns. The music drowned out the sound of the
mechanism. This was the kind of mechanics that Ludovico could understand
and appreciate.

The success of this entertainment so pleased Ludovico that Leonardo was
encouraged to present another amusing idea. This one was an “alarm
clock” and it utilized what we call today the mechanical relay
principle. When a small power is suddenly switched over, the power is
reinforced. The “alarm” clock worked by placing a shallow basin of water
at one end of a tubed lever. At the other end was another empty basin.
Water was led drop by drop into the second basin and as this slowly
filled the increasing weight lowered the lever. The shallow basin of
water at the first end was suddenly emptied and the immediate switch in
weight flipped the lever up and this in turn pushed up the sleeper’s
feet.


Leonardo decided to withdraw from the competition for the cathedral
dome. Although the cathedral authorities were pleased with his design,
they could not decide to whom the commission should be awarded. In the
summer of 1490 Ludovico was called upon to settle the issue and he
decided in favor of Antonio Amadeo from Milan. But the work that
Leonardo had done so impressed Ludovico that he sent him to Pavia in
company with an architect from Siena, Francesco di Giorgio Martini, to
inspect the work on the cathedral of that city. Leonardo, who had his
own workshop and apprentices now, took along one of them, Marco
d’Oggionno, a young boy of twenty.

In Pavia one of the greatest libraries in all of Italy was in the ducal
palace. Here Leonardo wandered among shelves of books and illuminated
manuscripts bound in rich velvets and gold-embossed leather all bound to
their places with silver chains. One book that he records in his notes
was written in the thirteenth century by Witelo, a Polish scholar, who
wrote extensively on perspective. Leonardo, by the necessity of his art,
had solved many problems in perspective. He had invented a pair of
proportional compasses, the forerunners of those used today for the
transfer of a drawing from one scale to duplicate the same drawing in a
larger scale. Leonardo had also designed in very careful detail a
parabolic compass for drawing a parabola in one continuous movement. He
now determined to write his own book on perspective and, as the subject
was so close to his studies of the eye, he would entitle it
_Introduction to Perspective, or the Function of the Eye_.

Leonardo submitted a number of plans for the completion of the cathedral
to the authorities in Pavia and then returned to Milan. He worked
through the rest of the summer on the equestrian statue and at the same
time he continued to expand his notes on anatomy, light and shade, and
perspective.

Late on a cold December night in 1490, Leonardo lit his lamp. This was a
very special lamp that he had invented. It had already created a great
deal of comment. It was so unusual, he had received an order from the
court for another which he made with a richly carved pedestal. Candles,
torches, and oil lamps, the only methods of artificial illumination in
those days, were poor substitutes for light. They flickered, smoked,
went out, and frequently caused damage with their hot drippings. As a
side result of his experiments in light, Leonardo had put a glass
cylinder in the middle of a larger glass globe. A wick in olive oil was
placed in the cylinder and the outside globe was then filled with water.
The result was a bright, steady light magnified by the water in the
globe.

He sat down by the small fire and arranged his papers in front of him.
Then, with a glance at his lamp, he picked up his goose-quill pen and
wrote, “No substance can be comprehended without light and shade; light
and shade are caused by light.”



                                   7
                               _Success_


It was January of 1491, and a light snow had fallen in Milan, edging
with white all the roofs, the massive spires of the cathedral and the
red battlements of the Sforza castle. Soon Ludovico was to be married to
Beatrice d’Este of the ducal house of Ferrara.

Once more the streets of Milan echoed to the carpenters’ hammers.
Messengers rode to and from the castle and endless carts full of
provisions pushed through the crowded city. Guests began to arrive from
all the allied courts of Italy with their bodyguards and servants. The
rooms of the castle, the palaces of the nobles, and even the inns were
filling with the royal processions.

Leonardo was again summoned by the court to prepare the decorations, the
costumes for the masquerades, and the arena for the jousting
tournaments. An invitation had been sent to all the friendly courts to
attend these contests-at-arms. So, accompanying each new party’s arrival
was a band of armored knights, their breast-plates, helmets, and shields
glistening in the winter sun.

Leonardo enjoyed designing mechanical toys and entertaining the guests
with them. One of these was a mechanical drum. Ordinarily most of the
entertainment began with normal drum rolls, but Leonardo’s rolls were
made on a kind of wheelbarrow. On it was mounted an enormous drum. When
the “wheelbarrow” was pushed, it put into motion a cogged wheel geared
to the axle. This wheel in turn was geared to two rotary cylinders with
pegs mounted around the top. The pegs moved against five drumsticks on
either side of the drum and thumped out a rhythm according to the
position of the pegs.

Ludovico’s marriage to Beatrice d’Este, a girl of little more than
fifteen years, further isolated Leonardo from the court. Being almost a
child, Beatrice loved parties and festivities, and she surrounded
herself with people who catered to her frivolous whims. As a result so
serious a man as Leonardo was forced into the background of the court
life. He was called upon more and more to act as stage-designer while
his more important work went unnoticed. Because these entertainments
were easy for Leonardo to design, they did give him more time to work on
his giant equestrian monument of Francesco Sforza. Working one day on
the scaffolding surrounding the clay figure of his statue, Leonardo
heard a knock at his studio door.

“Come in,” he shouted as he climbed down. “The door’s open.”

Three peasants cautiously entered the room and quickly took off their
caps. One of them was holding a carefully wrapped bundle.

“Master Leonardo, we have brought you some shells we found on a ridge of
Monferrato. Remember, you asked us to bring anything we found that was
unusual?”

“Yes, Pietro. Thank you. Put them here on the table.”

Leonardo opened the bundle. He smiled when he saw the shells. He
remembered how, as a young boy, he had found seashells like these high
in the mountains. Leonardo questioned Pietro and his companions as to
where they had been found and under what circumstances. He gave them
some coins and, when they had gone, he looked among his growing
collection of notes and drawings on the shelves. It took some time for
him to find what he wanted, for the pages were in such confusion.
Finally, he sat down at the table with several of the sheets and,
putting the seashells in front of him, he began to make notes.

The shells were fossil shells but, thought Leonardo, their presence on
the high mountains of Lombardy could hardly be attributed to the great
flood as described in the Bible. In his notes, Leonardo cited the case
of the cockle which, out of water, is like the snail. It makes a furrow
in the sand and can travel in this furrow about three to four yards a
day. By such means, he calculated, it could not possibly have reached
Monferrato from the Adriatic in forty days (which was supposed to have
been the duration of the flood)—a distance of 250 miles. Nor were these
simply dead shells deposited by the waves—for the living creatures are
recognized by being in pairs, and these in front of him had certainly
been traveling in pairs. Consequently, they could have been left there
only when they were alive and the mountains were covered by the primeval
oceans. Moreover, Leonardo also described how living matter in
prehistoric times fell into the mud and died, and how this mud, as the
waters receded and years had passed, was changed into rock forming a
mold about the fossil—literally making a cast of its original living
appearance.

By such deductive reasoning and the testing of the evidence before him
against the common beliefs, Leonardo struggled to free the minds of men
from medieval superstitions and beliefs. Indeed, these medieval
superstitions existed everywhere. Astrologers, or men who told fortunes
by the position of the stars at a given moment; and necromancers, those
who by tricks of magic claimed to be able to talk to departed
spirits—these men profited from the ignorant. The Church, with its
preaching of devils and hells, provided the background against which
these fakers flourished.

Ludovico Sforza was himself a believer in such things. His own physician
and astrologer was a man by the name of Ambrogio da Rosate, who had such
influence over the court that he was given a post in the University of
Pavia, and his fame was so great that he was called upon to predict the
future of Pope Innocent VIII! Leonardo’s dislike of these men was
intense. He scorned the supernatural and asked men to look about them at
the real world and the real heavens. Observation and experiment—these
were Leonardo’s key words. But he was a lonely figure in his
thinking—like a man awake while the rest of the world slept.

At last the full-size model of the Sforza monument was nearing
completion. Ludovico had ordered it ready for exhibition in the
courtyard of the castle for yet another marriage festival that was soon
to take place. This time it was the marriage of his niece Bianca Maria
to Maximilian I of Germany. Leonardo and his assistants were busy with
the finishing touches on the monument, and with building a wagon on
which to carry it from the studio to the courtyard.

During these last months Leonardo had had to struggle with all kinds of
heavy loads. Already he had improved on pulleys by inventing a new kind
of tackle, and he also had utilized many kinds of levers. One of his
simpler discoveries for raising heavy weights was a jack which, in
appearance and principle, was the forerunner of our own automobile jack.

In 1493 when the clay model of the Sforza monument was completed, it was
put on the cart and wheeled to its place of exhibition where a curtain
was thrown around it. Again Milan was the host to a gathering of noble
courts, and this time Ludovico outdid himself in the display of luxury.
Tapestries hung from the buildings and rich carpets were laid down the
steps of the cathedral. Everything that Milan had to show was on
exhibition—even a crocodile.

But the most impressive sight of all was the unveiling of Leonardo’s
colossal statue. It rose in majesty against the red walls of the castle.
The name of Leonardo da Vinci was suddenly on everyone’s lips. As the
word of his artistic achievement spread from city to city, messages of
praise came pouring in. And, for a while the years of frustration and
failure to gain recognition melted away. Leonardo at forty-one had at
last achieved some success.

Now there was a breathing spell, and Leonardo returned to some of his
own projects. For a long time he had continued his observations of his
two favorite elements—air and water. To him they were related in their
movements. The birds flying in the currents of air and the fish swimming
in the flow of water seemed very similar to him. He had already designed
various instruments to tell him about the direction of wind and its
velocity, and he had also commenced to analyze the wing structure of
birds and bats. To soar through the air like a bird was an ancient dream
of man, yet for Leonardo it had become a passion. Ceaselessly, he
sketched the flights of birds, the flutterings of butterflies and
analyzed their flying patterns.

But to Leonardo, understanding the _dynamics_, or motion, of air was the
most important thing. He built an _anemoscope_, an instrument like a
weather-vane for telling the direction of the wind; and, he also
constructed several types of _anemometers_ for measuring the velocity or
force of the wind. One of these latter consisted of a thin rectangle of
metal hanging straight down in front of an upward-curving wooden arc.
This arc was marked off in units of measurement. When the wind blew, it
pushed the thin rectangle up the arc; thus, by noting at which gradation
it stopped, Leonardo could tell the velocity.

In addition, Leonardo at this time constructed a device which has been
compared to the modern instrument used for testing the weight-carrying
capacity of airplane wings. He fashioned a wing resembling a bird’s wing
and attached it to a lever so that it would be possible to lower the
wing by pushing rapidly down on the lever. This wing in turn was mounted
on a plank that was in weight equal to that of a human being. He then
calculated that two wings of this kind would have to be about twelve
meters wide and twelve meters long to raise a man and his machine
together. Another device resembling those found in airplanes today that
Leonardo constructed was an inclination gauge. He made this by
suspending a heavy ball on a cord within a glass bell. This ball was
then supposed to guide the flyer by telling him whether he was flying
level, diagonally, up, or down.

    [Illustration: _One of Leonardo’s anemometers. The wind blew against
    the strip of metal, pushing it up the curved gauge and thereby
    measuring the force of the wind._]

    [Illustration: _Leonardo’s inclination gauge, designed to guide a
    man in flight. The ball in the glass cylinder was supposed to tell a
    “flyer” whether or not he was flying level or tipped._]

To Leonardo, water was also a phenomenon that from his youth never
failed to excite his curiosity. The use of water power to run machines,
to irrigate fields and to carry boats inland was a subject that he never
ceased investigating. Out of his experiments at this time he constructed
a device for raising water to high levels. It was based on the geometric
spiral of Archimedes. He took a piece of gut, inflated it, and let it
dry. Then, covering it with a coat of wax to make it waterproof, he
wound it around a thin staff in a spiral. He put one end in a stream and
attached it by gears to a cogged water wheel; this set the long screw to
turning, and he was able to raise water from a low level to any height
he desired. With a multiple system of these screws he could raise water
in continuous circulation to the reservoirs on the highest towers.


In the year 1494, King Charles VIII of France crossed the Alps at the
head of an army of twenty-five thousand men. Now Ludovico, by a series
of diplomatic maneuvers, had allied himself with Charles and had, by
secret negotiation, actually invited the invasion. By such an alliance
he hoped to use Charles’ army to overcome the forces of the Pope which
stood in the path of Ludovico’s ambition to become the most powerful
ruler in Italy. Outwardly Charles was asserting his rights to the
Kingdom of Naples, but inwardly he dreamt of leading a crusade against
the infidels in the Holy Land. At the same time young Gian Galeazzo
Sforza, Duke of Milan, was dying. Ludovico desired this title for
himself; however, until Galeazzo was out of the way, he could not have
it. There were ugly rumors that young Sforza had been poisoned.
Moreover, in 1494, the Medicis—another powerful obstacle—were expelled
from Florence, and a republic was established.

Soon young Gian Galeazzo died, leaving a son, Francesco. This son was
the rightful heir to the Dukedom of Milan but Ludovico usurped the boy’s
claim and declared himself Duke of Milan. Now Ludovico was in a position
to await the impending battle between Charles and the Pope.

With such military and political ambitions in mind, Duke Ludovico now
assigned Leonardo the task of reviewing Milan’s defenses. Again Leonardo
submitted to Ludovico his plans for strengthening fortresses and designs
for new ones. The great architect Bramante was also assigned the task of
seeing to the city’s defenses, and for some time the two brilliant men
worked together.

Then, in the spring of 1494, Leonardo was sent to Vigevano where
Ludovico’s young wife was staying. This town was also the birthplace of
Ludovico, and Leonardo was given the job of designing and building a
small summer house and garden there for Beatrice. In addition, Leonardo
built a kind of “air conditioner” for her bedroom. It consisted of a
large waterwheel that cooled the air circulated into her room. Although
this ancient device had long been known to the Greeks and Romans,
Leonardo was the one who succeeded in perfecting it.

During this time Leonardo’s highly original mind was also at work on
other devices. One of these was an _odometer_, an instrument for
measuring the distance traversed by a vehicle. Dials, turned by a system
of gears attached to the wheel of a wheelbarrow, measured the distance
traveled as the barrow was pushed along the ground. In addition,
Leonardo conceived a kind of odometer to be used at sea; this consisted
essentially of a spinner that was towed by a ship which registered its
speed. Leonardo even invented an automatic spit operated by metal vanes
mounted in the chimney that revolved with the pressure of the hot air
rising from the fire—and a pair of large floating shoes for walking on
water!

In the meantime, Charles VIII of France had marched through Rome and
entered Naples. The conquest was without opposition. Charles was then
crowned King of Naples and all Italy was at his feet. Yet his triumph
was a short one. Ludovico, having used the king to get rid of his
enemies, now plotted against the king himself. He formed an alliance
with the Pope, Venice, Spain, and the German emperor. Charles, faced
with this league, hastily beat a retreat to France. Fighting his way to
the border, he there signed a peace treaty. Thus Ludovico had swept
Italy clean of all opposition and was now the most powerful prince in
the land.

Yet Ludovico was quick to realize that his position could only be held
by force and he set about strengthening himself and his allies. To
provide for more cannons, a hundred and fifty thousand tons of bronze
were sent to manufacturing works in Ferrara. This, however, included the
very bronze Leonardo needed for the casting of his equestrian statue,
and this is why the statue was never cast. Years of Leonardo’s work now
seemed to vanish overnight. Ludovico also needed large sums of money to
secure friends in high places and Leonardo’s own payments were suddenly
dropped. Forced again to worry about paying for his daily bread and for
his household and apprentices, he wrote letters to Ludovico complaining
of his lack of funds and asking for money that was owed him for work
done. He looked about for other commissions, but none were available.
Moreover, because he was still court painter to Ludovico, he was ordered
to paint the decorations of some rooms in the castle. But this was more
than Leonardo could take—he walked off the job without finishing it.

Despite all of these misfortunes, Leonardo continued struggling with the
problems of flight. He kept working out the proportions of wing span to
the weight of the load. Indeed, he had already started designs for a
flying machine. He had chosen a room which was the highest in one of the
towers of the castle and which had access to a roof. Leonardo’s plans
for a flying machine were a secret, and, with the exception of an
assistant, no one knew about them. He made sure that he could not be
seen by the workmen on the dome of the cathedral and proceeded to block
off his room with beams which he planned to use as supports for his
model.

He had thought at first that any attempted flight should take place over
water in order to cushion a possible crash—but as his plans progressed
he designed a parachute. It was a pyramid-shaped “tent of linen”
twenty-four feet broad and twenty-four feet high, and it is believed to
have been successfully tried out from a tower especially constructed for
that purpose.

Since Leonardo was no longer working for Ludovico, he lived more simply
than ever. He made regular lists of his expenses down to the last penny.
His habits were frugal although he always kept himself neat. His meals
were spare; he drank a little wine at meals and never ate meat. To his
pupils and apprentices, he recommended regular habits such as not
sleeping during midday, eating only when hungry and chewing well,
exercising moderately, and sleeping well covered.

Yet, even though Leonardo lived cheaply, he was now greatly in need of
money. Swallowing his pride, he wrote to Ludovico, placing himself at
the duke’s service once again. His absence from court, he said, had been
necessary so that he could earn a living. In this and other ways,
Leonardo attempted to heal the break between them.

It turned out that Ludovico was glad to have Leonardo back. Perhaps
mindful of the fame that the model of the equestrian monument had
brought the house of Sforza, he now commissioned Leonardo to paint a
picture. The Dominican monastery of Santa Maria delle Grazie was the
nearest church to the Sforza castle and a favorite retreat of Ludovico.
Here he used to walk in the quiet garden while the white-robed monks
silently went about their chores. In gratitude for the peace he found
there, Ludovico had had the refectory rebuilt and on the back wall, a
crucifixion scene had been painted by Montorfano, a Lombard. But the
front wall was given to Leonardo. On this Leonardo decided to paint a
picture of the Last Supper—the painting that has since become one of the
best known in the world.



                                   8
                              _The French_


The noonday sun was baking the deserted streets of Milan as Leonardo
hurried across the drawbridge of the castle. The guard dozing in the
entrance arch started to his feet, but when he saw who it was he sat
down again, muttering about a madman. Taking the shortest way, Leonardo
arrived at the monastery gate and pulled on the bellcord. When the gate
opened Leonardo brushed past the startled monk and made directly for the
scaffolding in the refectory. He looked at his almost completed painting
for a moment, took a brush and mixed a color swiftly on the large
palette. Then he climbed the scaffolding and very quickly applied three
or four strokes. With this he sighed and smiled. Then, just as abruptly,
he put away his brushes and, without a backward glance, he left, making
his way back to the castle in the hot sun.

For three years, Leonardo had been working this way on the “Last
Supper.”

Sometimes he would work from dawn to dusk forgetting to eat; other
times, he would stay away for days and then run back just to add a
touch. Once he arrived and, with his arms folded across his chest, he
stood in front of it for two hours just studying what he had done.

Now, in 1498, the painting was nearing completion and the only faces
still left blank were those of Christ and Judas. Leonardo had drawn
hundreds of sketches, taking his models wherever he found them—once he
sketched a man just for his hands. Now that his name had become well
known he always had an audience while he worked. His pupils, the monks,
visiting nobility, church officials, and frequently Ludovico himself
watched him as he painted the “Last Supper.”

But Leonardo, as usual, was involved in many different tasks. He was
supervising the installation of a hydraulic pump over seventy feet high
beside a stream which would use the power of the stream itself to pump
water into the castle. Mindful, too, of the uncertainty of court
patronage, he was designing commercial machinery, hoping thereby to
secure an income outside the court. Among the most notable of these were
an olive press, an automatic file-cutter, a hydraulic saw, and a needle
sharpener. This latter was a forerunner of modern sharpeners with their
mass-production methods. With it, Leonardo dreamt of sharpening four
hundred needles at a time, or forty thousand an hour so that in twelve
hours one person could sharpen four hundred and eighty thousand needles!
The needles were arranged successively on a moving belt of leather and
brought against a rotating grindstone. This grindstone was set in such a
way that the needles were sharpened into curvilinear points rather than
the usual triangular points.

In his travels to Vigevano and other parts of the countryside around
Milan, Leonardo had studied flour mills. He had talked with the workmen,
asked the prices of grain, and noted the time that it took to do the
milling. Then he made calculations on ways to cut down the time, and, in
fact, redesigned the entire mill. He mounted twelve cylindrical
millstones in rows of four on one side of a canal and another twelve on
the other side. In the canal were hydraulic wheels or paddlewheels. Each
wheel was attached to a rod that ran underneath four millstones. Geared
to the one rod were four grinding levers to the stones above. In this
way it was possible to have twenty-four millstones operating at the same
time.

But most fascinating to Leonardo now was the construction of his flying
machine. His first models involved the principle of an air-screw mounted
on a platform on which a man stood. But where would the necessary power
come from to lift his machine from the ground? At first he thought of
operating his air-screw by means of a steel spring coiled around a drum,
but this he apparently abandoned. Later, however, Leonardo did design
another model on this principle which has been called the forerunner of
the modern helicopter. It was to be operated by four men standing on a
platform. Each man would hold a bar which wound a spring-driven
mechanism, much as in a modern clockworks. The air-screw was a broad
blade spiraling about a vertical shaft—the ancestor of the modern
propeller.

The model that Leonardo wanted to construct now, however, was of a
different principle. Instead of an air-screw he substituted a pair of
wings fashioned after those of the birds. There was still a platform on
which the flyer stood and two springs were still the essential “motor”
to raise and lower the wings. But as Leonardo worked on his apparatus he
began to realize that it would be too much at the mercy of a sudden gust
of wind or a violent updraft. It was necessary to return to his study of
the air and its currents.

With all of this activity in mechanical devices Leonardo had reawakened
his interest in mathematics. During this time he was introduced to a man
at Ludovico’s court who became his friend and collaborator. He was a
Franciscan monk named Fra Luca Pacioli who had been appointed a
professor of mathematics by Ludovico. He, too, came from Florence, and
in 1496, when he met Leonardo, he was forty-six years old and the author
of _Summa di Arithmetica_, the first printed scientific work of his
time. Pacioli was now at work on a book of geometry to be entitled _De
Divina Proportione_ and he enlisted Leonardo’s aid in drawing the plates
for his book. As Leonardo had already made a study of human proportions,
the association with Pacioli was of benefit to them both. Among
Leonardo’s best known drawings of human proportion is a beautifully
rendered figure-study of a standing man with his arms at his sides and
then outstretched, his legs together and then apart, inscribed within a
square and a circle. It was made to illustrate a passage from Vitruvius
on the proportions of a human figure and demonstrated, among other
things, “the span of a man’s outstretched arms is equal to his height.”

Moreover, Leonardo found with Pacioli confirmation of many of his own
observations and experiments and in turn Pacioli gave to Leonardo a
confidence in his own methods. Pacioli also helped Leonardo with his
arithmetic, a subject that Leonardo had neglected in his impatience to
study geometry. The association also helped to free him further from the
cobwebs of medieval beliefs. For Pacioli, the friendship with Leonardo
was a revelation. Although Pacioli was a learned mathematician, Leonardo
demonstrated to him that the application of his science encompassed
_all_ sciences—even art—for Leonardo later wrote, “Let no one read me
who is not a mathematician....”

Legend relates that Leonardo became so absorbed in his studies that the
prior of the monastery complained to Ludovico that the “Last Supper,”
although nearly completed, still lacked the faces of Christ and Judas.
Ludovico summoned Leonardo to court and laid the complaint before him.
Leonardo, however, was quick to reply.

“The good prior is an esteemed man, your Grace, but he is a monk and not
a painter. Little does he know that I spend at least two hours a day on
my painting.”

“But Master, he says he never sees you there, so how do you explain
these two hours a day?”

“Excellency, the figure of Judas must be of incomparable evil. Every day
I search for this face in the criminal quarter, and every day I fail to
find the evil that I am looking for. If I cannot find this man, however,
I can use the head of the prior—it would do admirably, but I have
hesitated for fear of hurting his feelings.”

Ludovico slapped his knees and roared with laughter. There were no more
complaints.

Finally, in 1498, the scaffolding was removed from the painting and
Leonardo’s masterpiece was revealed. The twelve apostles grouped at the
table are shown each responding in his own way to the words of Christ,
“One of you shall betray me.” Again hundreds flocked to see this latest
marvel of Leonardo’s. Its striking influence was felt by generations of
painters. Even now, more than four hundred and fifty years later, the
world still comes to stand before the genius of Leonardo da Vinci in the
refectory of Santa Maria delle Grazie.


The clouds of war were gathering again over Italy. In April of 1498,
Charles VIII of France died and his successor was Louis of Orleans, who
became Louis XII. The new King of France laid claim to the Dukedom of
Milan, and Ludovico again tried to form an alliance against him. But the
years of juggling enemy against enemy and friend against friend were now
coming to an end. No one trusted Il Moro any more, and suddenly he
realized that he was to be alone in this new fight. After nearly twenty
years of power sustained by powerful alliances, Ludovico was forced to
turn to his own people of Lombardy. Frantically he tried to correct the
injustices of years. The people had been cruelly taxed to support the
extravagances of the Sforza court, and, in addition, they had been badly
treated by petty government officials. Ludovico now sought to repay the
past miseries of his people and to rally them to his support. In such a
spirit he remembered his court painter, Leonardo da Vinci, and gave him
a vineyard and considerable piece of land not far from the Porta
Vercellina.

Now, for the first time in his life, Leonardo knew financial security.
With the income from the vineyard, and in the peace of his estate, he
was left free to follow his own researches. He took no notice that his
“peace” was surrounded by the threat of war. Indeed, he remained aloof
from politics and court intrigues as much as was possible for a man
living in the midst of such chaotic times.

Leonardo now had the opportunity to follow up an early interest—the
study of plants. He made many beautiful drawings; no plant was too small
to catch his eye. His notes on botany began to grow. With his genius for
observation and analysis of nature, Leonardo made some extraordinary
discoveries of botanical laws entirely unknown before his time. He wrote
of the phenomenon of _heliotropism_, or the movement of plants toward or
away from the sunlight. In addition, he described the phenomenon known
as _geotropism_, or the growth of plants according to gravitational law,
as for example, roots growing downward and shoots growing upward. He
also defined the laws of phyllotaxis, which describe the system or order
of leaf arrangement on a plant’s stem. That is, leaves are arranged
spirally around a stem so that the third leaf above grows out over the
third leaf below on one type of plant; or, on another type, the two
third leaves are over the two third leaves below. The same natural laws
apply to the branches of plants as well; they occur so that every leaf
and branch can receive sufficient air and light. Amazingly enough, these
laws, which Leonardo described so completely, were not rediscovered
until almost two centuries later!

Leonardo went even further in his botanical studies. He experimented
with gourds, planting them in various aqueous solutions; this
anticipated modern methods of growing plants in chemicals. He also
tested the actions of arsenic and mercury poisons in plants. He
reproduced the shape and form of leaves by pressing them on paper coated
with lampblack, a method that was not used again until the nineteenth
century. Carefully noted, too, in his writings was the rising of sap
from the roots to the branches by capillary action; this, too, was not
rediscovered until much later—in the eighteenth century. Leonardo also
extracted oils and essences from flowers and studied the influences of
altitude on the development of vegetation. Indeed Leonardo’s very
approaches to a systematic classification of plants were the forerunners
of modern methods of classifying.

In the seclusion of his own home, as he continued his studies of
geometry with Pacioli, Leonardo again turned to his observations of the
heavens. On the roof of his house he had set up a small observatory for
watching the sky at night. Often he looked at the stars through a
pinhole in a sheet of paper. Leonardo did this to stop the “twinkling”
of the stars which he recognized as an optical illusion. Moreover, by
looking at the stars in this manner, he noticed that some were larger
than others, and imagined to himself how our own earth might look from
them. Would we not be but another “star” in a vast collection of stars?
And if that were true—how could the earth be the center of the universe?
By the same imaginary reasoning, he speculated on how we must look to
someone on the moon. Realizing that the moonlight on earth faintly
illuminates the dark side of the earth, he reasoned that then there must
be an “earthlight” doing the same on the moon. Thus he was the first to
explain the dim reflected light on the dark side of the moon. Moreover,
Leonardo is known to have looked at the moon through a convex lens, and
perhaps even a form of telescope. Indeed, he had built telescopic-type
tubes with lenses in them and had written directions for their use. It
seems certain that at about this time Leonardo became convinced of the
heliocentric theory, the theory that states the sun is the center of our
universe. On a sheet of mathematical notes Leonardo wrote in large
letters, “the sun does not move.”

During this time he continued to seek out books on astronomy. Leonardo
was familiar with Aristotle’s _Meteorology_, Archimedes’ _On the Center
of Gravity_, and with _Problems in Aristotle’s Books of the Sky and the
World_, a work by Albert of Saxony. This last book Leonardo had to read
with the help of a Latin dictionary, because his Latin was not good. He
had already read Plutarch, who had defined the moon as a solid. Plutarch
had written further that the “spots” on the moon were the result of
shadows cast by irregularities on its surface. This theory, that was
apparently abandoned during the Middle Ages, supported the conclusions
that Leonardo had reached by his own observations. But he still
struggled against a mistaken idea of his own. For a long while he
maintained that there were seas and waters upon the moon which accounted
for the sunlight being reflected so brilliantly.

Meanwhile, in July of 1499, the French army had reached Lombardy.
Ludovico was now in a state of desperation. He tried to appeal to the
people of Milan, explaining that their heavy taxes had been due to the
constant threats from abroad. But, however hard he tried to arouse their
sense of loyalty to him, the public of Milan turned a deaf ear. They had
not forgotten how Ludovico had allied himself with Charles VIII—a
foreign king! Ludovico now had to put his trust in his army commander,
Galeazzo da Sanseverino, despite warnings that this was a man of
doubtful loyalty. Moreover, to make matters worse, Louis XII had
succeeded in forming an alliance against Ludovico; and, among his allies
was a powerful cardinal, son of Pope Alexander VI—the notorious Cesare
Borgia.

From a note on a page of designs for supplying and heating a bath we
know that Leonardo continued his quiet life, only vaguely disturbed by
the political upheaval taking place around him. His note reads, “On the
first day of August 1499 I wrote here of movement and weight.” He had
made many experiments and calculations concerning the movement and
weight of objects. He had drawn, for example, the flight of an arrow to
describe motion through air and although he wrote no specific formula,
he marked the three stages of its trajectory—the initial push, the
slowing and the steeper downward path as the arrow’s momentum was
overcome by the resistance of the air. He also defined the law of
movement on an inclined plane and he arrived at the root principle of
Newton’s law of gravitation when he wrote, “every weight tends to fall
toward the center by the shortest way.”

A diagram of this period is probably the first scientific graph.
Leonardo had experimented with two balls dropped from a height. First he
dropped them together and then one after the other. In attempting to
solve the mathematical problems presented by these falling bodies he
drew a graph of vertical and horizontal lines. The times it took for the
balls to fall were marked on the horizontal lines and the distances on
the vertical lines—thus, he could trace their relationship.

But this peaceful time of productive work was running out for Leonardo.
Ludovico’s commander, Galeazzo, had yielded the fortress of Alessandria
to the French at the first battle. Ludovico himself had sent his sons
and his treasure to his brother, Cardinal Ascanio, in Germany. When he
saw that his cause was lost, he turned the Sforza castle over to
Bernardino da Corte, a trusted commander, making certain that it was
fully supplied with arms and food. Then in sorrow, Ludovico Sforza, Duke
of Milan, left his city for the last time as ruler of Lombardy. The
gates of Milan were opened to the French in October of 1499, and
Bernardino da Corte surrendered the Sforza castle.

French soldiers now occupied Milan as conquerors and the people of the
city were in a state of confusion. Those who could made their peace with
the French; but others, who had been supporters of Ludovico, fled to
avoid arrest. Leonardo, who would be suspect to the French, packed up
his few possessions—although he did manage to retain his estate—and
left, together with Pacioli and an apprentice, for Mantua.

    [Illustration: _Leonardo had to flee Milan._]



                                   9
                            _Cesare Borgia_


Leonardo, Pacioli, and Salai, the apprentice, arrived in Mantua in
February of the year 1500. They were given refuge in the castle of
Isabella d’Este, who was the sister of Beatrice, and the wife of
Francesco Gonzaga, governor of Mantua. Isabella was one of the eminent
women of her time and attracted to her court the intellectual life of
Italy. In Leonardo she recognized the man of genius; indeed, she treated
him as an equal, putting her castle at his disposal. She persuaded him
to paint her portrait and Leonardo commenced a preparatory drawing.

In the evenings at the castle there were discussions and music and here
Leonardo again met his pupil and companion on the trip from Florence so
many years ago—Atalante Migliorotti who had left Milan in 1490 to assume
the post of court musician to Isabella.

Although Leonardo had found a haven of peace in the political storm that
raged about the city state of Mantua, he and Pacioli took to the road
again for reasons unknown. Isabella d’Este, who still wanted Leonardo at
her court, sent many a letter and messenger in the following years to
bring Leonardo back—first to finish the portrait and then, when that
failed, to sell to her any picture that Leonardo wished to send.
Strangely enough, however, Leonardo seems to have turned his back upon
the one sympathetic person he had met in a world of indifference.


The first, warm breezes of spring were blowing over the lagoons of
Venice when Leonardo and Pacioli stepped ashore on the Piazzetta, or
Little Square of San Marco. But the beauty of this jewel-like city
rising from the sea was momentarily ignored by the two travelers for an
angry, frightened crowd had gathered about the Doge’s palace on the
Piazzetta.

The people of Venice were fearful because their fleet had just suffered
a crushing defeat by the Turks. This meant that their power at sea, once
supreme, was now no more. Year by year, moreover, their possessions in
the east had been slowly whittled away, and now the city itself was
threatened by invasion. At this same time, the Venetian ambassador,
Manenti, hoping to make peace with the Turks, had been rudely rejected
by them. Panic soon swept the city and rumors of the bloodthirsty
infidel passed from person to person like the rush of an ugly wind.
Barricades were put up and windows were barred. In this charged
atmosphere, Leonardo and Pacioli sought out their lodgings.

Soon after Leonardo’s arrival here—either because his reputation had
preceded him or, more likely, because of Fra Luca Pacioli’s
recommendations—he became directly involved with the defenses of Venice.
Immediately he was sent on an inspection trip of the city’s existing
defenses, especially those inland from where an invasion would probably
come. When he had seen them, he recommended a system of defenses along
the Isonzo river near the present border of Yugoslavia, using the river
itself to the disadvantage of the enemy. He also made suggestions for
the improvement of forts, and even drew up plans for a completely new
type—a circular fort. This consisted of a central, circular fort
surrounded by two belts of fortresses each separated by a moat. In the
outside moat were four semicircular outposts. Communication was by
underground galleries. The total absence of superstructure and
projecting balconies was a new idea for the times. Another new defense
idea was to station in the moat itself a low, thick tower almost
completely submerged, defended by a thin opening near the waterline. It
was reached from the main fort by an underground passage and the
gunsmoke was removed by vents. According to Leonardo no enemy could
conceal himself in any part of the defenses and not be seen from such an
outpost.

Leonardo’s most unusual scheme for defending Venice, however, was his
idea of approaching an enemy fleet under the water and then putting
holes in the hulls of their ships. Actually, the idea of diving was not
a new one. Aristotle had written of diving and diving bells, and
certainly the stories of pearl fishers in the Orient were well known in
the Renaissance. But Leonardo designed a diver’s suit closely resembling
those used today. This consisted of a complete suit of leather with
helmet and eyepieces; it was made airtight by spirals of steel at the
joints. He then added a bladder for holding air which fastened inside
the suit at the diver’s chest. It is possible that Leonardo also
invented an air chamber that could be used by the diver while under
water—but he was very secretive about this invention for fear of how men
might abuse such a discovery. He wrote, “... and this I do not publish
or divulge, on account of the evil nature of man, who would practice
assassinations at the bottom of the seas....”

Leonardo felt the same way about a “submarine” that he presented to the
Councilors and Tribunal of Venice. This resembled a turtle’s shell with
a raised bump on the center which was the “periscope.” When submerged
the water probably rose to an area just around the “periscope,” but,
again, the information about its air-supply is missing and the only
reference to it is a reminder to close the “l—.” In addition, he
invented a system of screws mounted in tongs with the borer in the
middle for putting holes in the bottoms of enemy ships, and at the same
time he thought of a defense against such an attack by designing the
defending vessels with double hulls.

Among Leonardo’s other maritime devices were designs for boats that
could dredge canals, harbors, and lagoons. What was the result of all
these plans? We do not know. Whether any one of them was used against
the Turks is a mystery.

At any rate, Leonardo and Pacioli left Venice that same spring and
arrived in Florence in April of 1500. One of the purposes of Leonardo’s
journey was to visit his father who was now living on Via Ghibellina
with his fourth wife. Leonardo was now forty-eight. Still tall and
straight with the strength of his youth, his face prematurely aged and
his hair thinning back from his high forehead, Leonardo was more than
ever an outstanding looking man. He still scorned fashionable clothes
and dressed according to his own comfort which made him even more
noticeable among the crowd. His deep-set eyes with their direct and
penetrating glance, framed by his full, reddish beard, never missed a
thing, although he now wore spectacles at his work.

Now that he was back in Florence, Leonardo needed lodgings and a job. He
had banked his small savings, and he did not want to touch that. His
father’s house with the five children of his present wife plus the sons
from his previous marriages was too full to accommodate Leonardo.
Moreover, the relationship between Piero and Leonardo was polite but
distant, as Piero preferred the children of his later marriages.

Luckily, the place to live and the commission Leonardo needed presented
themselves at the same time. The Church of the Annunciation of the
Servite Order of Monks needed an altarpiece, and, as Leonardo’s fame was
great, they offered him and his apprentice quarters in the monastery.
Here, in the solitude of a monastic cell, Leonardo was able to return to
his own researches. His long association with Fra Luca Pacioli continued
as they worked together on Pacioli’s edition of Euclid’s _Elements_. At
the same time, with his absorption in geometry, Leonardo commenced his
studies of the transformation of solids; that is, changing the shape of
something to another shape without diminishing or increasing its
substance.

In his preoccupation with geometry, Leonardo had apparently done little
about the commission which the Servite monks had given him. He finally
yielded to their complaints, however, and commenced to draw the
preliminary study for the subject, which was “St. Anne with the Virgin
and Child.” Again his knowledge of geometry is most apparent in the
finely constructed composition, every gesture of which is as plotted as
a geometric exercise. In April of 1501, the drawing was finished; it
caused an immediate sensation throughout Florence. For two days the
public was allowed to pass in front of it.

But now a change was taking place in Leonardo. He was no longer content
with simply painting. His highly original researches for pictures had
slowly grown to the point where the research was more important than
painting. In a sense the scientist had taken the brush from the artist.
In two letters from Isabella d’Este’s emissary in Florence we learn, “He
is entirely wrapped up in geometry and has no patience for painting.”
This excerpt from a letter dated April 8, 1501, was followed six days
later by another which said in part, “In brief, his mathematical
experiments have made painting so distasteful to him that he cannot even
bear to take up a brush.”


A few months after the completion of the St. Anne drawing, Leonardo
received a letter signed by Cesare Borgia, Duke of Valentinois. Leonardo
frowned and thought back to his last days in Milan. When King Louis XII
of France had entered the city, he had summoned the painter of the “Last
Supper” to an audience. The king had been generous in his praise and had
tried to persuade Leonardo to remain. At that same audience had also
been Cesare Borgia, an ally of the French. Leonardo remembered the man
now—the dark hair and eyes, the black, arched eyebrows, and the face
marked by some old disease. He was a powerful-chested, thin-hipped man
who had originally been made a cardinal by his father, Pope Alexander
VI. But the attractions of secular power soon persuaded him to abandon
this title. With the enthusiastic help of his father, Borgia had fought,
murdered, and deceived his way to a formidable position of authority in
these last years. Leonardo, in the seclusion of the monastery, had
lately heard that Borgia’s army had even been at the gates of Florence.

The letter addressed to Leonardo was an offer to assume the post of
Architect and Military Engineer to His Excellency, Cesare Borgia. He
thought of Ludovico Sforza—defeated and captured at the battle of Novara
just a year ago as he attempted to regain his dukedom. Now the duke was
a prisoner at Loches in Touraine; Leonardo had written of him, “The duke
lost his State, his personal possessions and his liberty, and none of
his enterprises have been completed.” And Leonardo also thought of his
equestrian monument still standing in the castle being used for target
practice by the French archers. Like the duke, nothing of his own had
been completed either. Perhaps this Borgia offer was an opportunity.
Leonardo decided to accept it.

In May of 1502, after having presented himself to Cesare Borgia in Rome,
Leonardo began his hectic travels through Tuscany and Umbria. He was to
inspect the fortresses and cities of Cesare’s new conquests there, and
to make whatever recommendations he felt necessary for their
improvements. Arriving in Piombino, he at once set down a project for
draining the marshes and reclaiming the land. Also, while he was here,
he spent hours by the sea watching the waves curl in from the Adriatic
and studying the crash of water over the beaches. Moving on to Arrezzo,
he drew up the first in a series of remarkable maps for the army of
Vitellozzo which, with the backing of Cesare Borgia, was marching
against Florence. These maps are bird’s-eye views of Tuscany and Umbria,
and somewhat resemble modern aerial photographs. Drawn from Leonardo’s
own observations, the green mountains stand, according to their height,
in relief, with the roads winding over them and down through the
valleys. The streams and their tributaries are in blue and even the
villages and cities are drawn with great exactitude. Indeed Leonardo had
learned his lessons from old Toscanelli well, and he was one of the
first to bring the art of cartography to such perfection.

In July and August Leonardo was in Urbino and Pesaro, and by the 8th of
August he had reached Rimini. Here he strengthened the fortifications
and then rode quickly on to Cesena. Between Cesena, capital of the
Romagna, and Porto Cesanatico, he spent from the middle of August to
September planning a canal between the two, redesigning government
buildings, and drawing up a new quarter to be built for the city of
Cesena. At this time he constructed an instrument for telling him the
speed of water currents in a stream. It told him whether the flow was
swifter at the surface or at the bottom or on one side or the other of
the stream’s bed.

In the meantime, Florence, alarmed at the growing power of Cesare
Borgia, appealed to Charles d’Amboise, Regent of Milan for France, to
come to her aid. Charles responded in the absence of the French King and
helped to protect Florence. The enemies of Cesare took advantage of this
to form an alliance, and soon Cesare was being forced back from his
newly won possessions. Cesare himself then hastened to Milan, and there
he suddenly came face to face again with Louis, the King of France, who
was on his way to Naples. Borgia, who could exert great charm and
influence when he wished, persuaded the king that, all rumors to the
contrary, he, Cesare, was fighting the enemies of France. Again he won
over the French, which greatly strengthened his position. Then, from
Pavia, he issued a decree placing every facility possible at Leonardo’s
disposal. In addition, he instructed all officials to help Leonardo in
every matter, referring to him as “our highly esteemed court architect.”

While Leonardo was in Porto Cesanatico, a delegation from Bayzid II,
Sultan of Turkey, paid a visit to Cesare Borgia. Among other things the
delegation was looking for an engineer to build a bridge between
Constantinople and Pera to replace a temporary wooden structure.
Leonardo designed for them a single-arched bridge with double ramps at
either end (looking very much like a present-day “thruway” entrance). He
provided that it should be approximately twelve hundred feet long,
eighty feet wide, and one hundred and forty feet above the water.

    [Illustration: _Da Vinci’s proposed bridge from Constantinople
    (Istanbul) to Pera. Looking very much like a modern “thruway”
    entrance, it was to have double ramps on both sides._]

In his travels through the countryside, Leonardo could not help but
notice how primitive the mills were. Feeling how strongly the wind blew
in from the sea, he designed a windmill with a roof that turned with the
sails. For the mechanism inside he devised a band brake—a semicircle of
wood into which the large cogwheel of the mill was forced. This mill
resembles the “Dutch” mills of the Netherlands and was among the first
of its type to be brought into existence.

In the fall Leonardo was at Imola. There he created another of his
beautifully rendered maps. He drew this with the help of a magnetic
compass of his own invention. It consisted of a board with an arc on it
and a compass needle, and was probably the first magnetic needle on a
horizontal axis. This time the map was of the city itself, the walls,
the castle and the principal buildings all touched with color and the
river winding through the fields. Drawn in the shape of a circle, it
resembles a view through a telescope from directly above. In Imola, too,
he met Niccolò Machiavelli, the famous historian and political
scientist, who was an emissary from the Signoria, the Council which now
governed Florence. These two men became friends and, later,
collaborators in Leonardo’s scheme to make the Arno river navigable to
the sea.

At this time Cesare Borgia, having achieved great success in his
military campaigns and confident of his conquests, decided to return to
Rome. With the disbanding of Borgia’s headquarters at Imola, Leonardo’s
duties were finished. Together with his new friend Niccolò Machiavelli
and two other Florentines, he left Imola and the service of Cesare
Borgia to return to Florence.

In January of 1503, a mathematician named Giovanni Battista Danti
attempted a flight in a machine that he had designed. This flight was
part of the entertainment at a wedding reception in Perugia. Danti
climbed into his apparatus on top of the tower of St. Mary of the
Virgin. It was pushed off into the air, hovered a few seconds, then
began slowly drifting toward the ground. But suddenly, one of its wings
hit a building projection and it crashed. Danti was carried away with a
broken leg.

The news of the event traveled quickly to Florence.

When Leonardo heard about it, he eagerly questioned all those who had
either seen it or had heard it described first hand. Danti’s attempted
flight excited Leonardo for now he realized that he was no longer alone
in his search. With a sense of urgency he returned to the problems of
flying. He felt now that the solution to flight might be in the swift
gusts of air through the ravines and the spread wings of the eagle
drifting high in the sky.



                                   10
                           _Shattered Hopes_


Before Leonardo could return to the problem of flight, however, he was
again faced with the necessity of supporting himself and his growing
household. The small fees he received for taking on apprentices hardly
covered the cost of housing and feeding them. Moreover, the equipment he
had to buy for his scientific researches added further to his strained
budget. So, when a servant from Francesco del Giocondo, a rich
Florentine merchant, presented himself at the gate with the request that
Leonardo accept a commission to paint Francesco’s wife, Leonardo was
only too glad to accept. The name of Francesco’s wife was Madonna Lisa,
or Mona Lisa for short. Leonardo painted her portrait on and off for the
next three years. Thus, what started as a minor commission ended as the
one painting—in addition to the “Last Supper”—that most people today
associate with the name of Leonardo da Vinci.

Having secured this work, Leonardo turned back to his studies of birds
in flight and the nature of air. The soaring wings of eagles and hawks
and the way they rode the currents with hardly a dip of their spread
wings guided Leonardo’s thinking from pure mechanics to machines that
act more on the principle of the glider. He proposed to write a treatise
on the nature of birds’ flight, and, with his usual thoroughness, he
began to weigh, dissect, and reconstruct various types of birds and
their wing structure. He realized that one of the main difficulties of
gliding was maintaining balance, or, more accurately, maintaining the
center of gravity. From previous observations Leonardo had noted that
man is capable of making the same motions that a bird does. He had also
measured the strength of a man’s legs and had calculated that man has
twice the power in his leg muscles that he needs for standing.
Consequently he began to redesign his machine making use of man’s arms
and legs to operate or “flap” the wings instead of standing him on a
platform.

The first of Leonardo’s new designs was a sort of harness apparatus
strapped across the shoulders of the flyer who was supposed to be able
to keep himself balanced by moving the lower part of his body. He could
manipulate the flight by handles that were connected to the flexible,
outer parts of the wings. These wings were designed from the webbed
wings of the bat. Surprisingly enough, this device closely resembled the
experimental gliders used by Otto Lilienthal almost four centuries later
in Germany.

Leonardo was now approaching other solutions to pure flight when further
hostilities interrupted his work. Florence and Pisa were in bitter
rivalry, and their struggle had assumed the proportions of a major war.
The Florentine army was now practically at the gates of Pisa. Niccolò
Machiavelli urged the Signoria to enlist the help of Leonardo da Vinci,
who might be able to think of an immediate plan for destroying Pisa and
her army. Never one to think in terms of an immediate battle or a
temporary success, Leonardo put forth a daring and sweeping plan that
would forever reduce the power of Pisa. The plan was as simple as it was
monumental—divert the Arno river from its course into two canals that
would empty into the sea at Leghorn south of Pisa. In this way, Pisa
would lose her water supply and her opening to the sea.

The plan met with immediate approval and by the end of July 1503,
Leonardo was sent out to survey the entire course of the river. He was
accompanied by Giovanni “the Piper,” a man who was frequently employed
on minor engineering projects and who was the official player of the
pipes to the city of Florence. Giovanni was also the father of Benvenuto
Cellini, who became the most famous goldsmith of the Renaissance. As
they made their way to Pisa, Leonardo made some more of his
extraordinary maps of the area, paying particular attention to the
course of the Arno and its tributaries. These maps later inspired him to
plan a whole series showing the main watersheds of Italy.

When he rode into the Florentine camp drawn up before Pisa, Leonardo
designed from his observations and maps, a dam on the Arno to regulate
the course of the river. This bird’s-eye view map is a marvel of
exactness. It shows the flow of the river hitting the dam with its
swirling backwash and overflow. Leonardo’s knowledge of the movement of
water was so great and his craftsmanship in drawing so fine that the
water in this map seems to flow before one’s eyes. One of the main
problems in regulating the Arno was its tendency to continually be
shifting its bed by the deposits of new sediment, and Leonardo realized
it would be a long time before this project could be completed.

When he returned to Florence he presented to the Signoria, as part of
his survey, various machines to hasten the excavation of the Arno. He
had designed a crane that would assist in the digging out of two
different levels at the same time. He also submitted the results of his
calculations on the saving of muscular energy by the use of such
machines. In addition, Leonardo proposed to use the water in the canals
for irrigation purposes and had even calculated what the volume and
velocity of a jet of water would be if projected from an opening in the
bottom of the canal wall into an irrigation ditch. As if this were not
enough, he had invented a practical method of piling as a foundation for
the lock-basins to protect them against the dangers of erosion.

A separate map of this period on the flow of rivers in general was
intended to relate to his treatise on the nature of water. In this
treatise is the first outline of the fundamental principles of
hydrodynamics, as for example:

The velocity of a current increases with the slope and decreases with
the winding of the riverbed.

The volume of a river is in proportion to the width of its bed, the
slope and the depth of the water being equal.

The slope and width being equal, the speed of the current is greatest in
the deepest part of the river.

The excavation force increases at the narrowest section of the river.


Because of the grumbling of the military commanders at what they
considered a waste of time, Machiavelli had to intervene with the
Signoria before Leonardo was sent out again with documents of authority
to continue with his plans. He spent well into the fall surveying the
Arno and in October he was back in Florence.

Meanwhile the fighting between Pisa and Florence had been lessened by
two political changes. In August Pope Alexander VI had died and his son
Cesare Borgia became seriously ill. The Republic of Florence was now
free of its most dangerous enemies—the Borgias. The city relaxed in its
new security and the hostilities between Florence and Pisa died down to
an uneasy armed watch.

Leonardo quickly took advantage of the situation to present an early
dream of his to the Signoria. He again put forth his idea of a
commercial canal to the sea and made mention of the great advantages
there would be for all the mills, lumber yards, forges and other
commercial interests in utilizing the water power that would be
available from his project. Piero Soderini, the governor of the
city-state of Florence, was impressed and thought of the glory it would
bring to Florence and himself. He told Leonardo he would present it to
the Signoria.

Leonardo now plunged into a winter of great activity. Forced to draw
from his savings, he had rejoined the guild of painters in October of
1503, and then applied for the commission of painting the murals in the
council chamber of the Palace of the Signoria. It had been planned to
decorate this great hall with scenes commemorating famous Florentine
victories, and Leonardo chose the battle of Anghiari where the soldiers
of Florence defeated the Milanese in 1440. In addition to working on the
“Mona Lisa” and continuing with the canal project—for which he was now
designing great suction pumps to lift rivers from one level to
another—he turned again to astronomy and geology.

Leonardo, while investigating the course of the upper Arno, had come
across much evidence that the land there had at one time been completely
under water. Various types of ancient ocean life and vegetation lay
scattered in layers along the ridges of the mountains, and these
Leonardo collected and brought back to his studio. He wrote, “above the
plains of Italy where now birds fly in flocks, fishes were wont to
wander in large shoals.” He reread Ptolemy, the ancient Greek geographer
Strabo, and even Sir John Mandeville, an English author of travel books,
in his quest for knowledge of distant places. He talked to travelers,
sailors, and wrote to friends to send him information about the
countries they had seen or lived in. Strabo, in particular, had set
forth the doctrine that the earth’s transformation had taken place by
the forces of volcanoes and water, but the wisdom of these early men had
been obscured by the closed minds of the Middle Ages.

Even in his own time of reawakening knowledge—the Renaissance—Leonardo
had to contend with the combined superstition of the Church and the
ignorance of misguided scholars. For example, the Church believed in the
great flood, as described in the Bible, and the scholars claimed that if
what Leonardo said were true—that the earth was the result of an
evolutionary process—there would have been written records. To this
latter Leonardo responded, “... sufficient for us is the testimony of
things produced in the salt waters and now found again in the high
mountains far from the seas.” But Leonardo’s conception of the evolution
of the earth was mistaken in one respect. He regarded the earth as
organic—living—and the flow of water he believed to be like the flow of
blood in man. Indeed, according to Leonardo, all living creatures were
reflections of a living, breathing earth. It was only when he again
turned his eyes inquiringly toward the moon and the laws of the universe
that he began to realize his error.

It had been the idea that the earth was the center of the universe which
supported Leonardo’s theory of an organic earth. Yet after years of
observation and study he abandoned this theory and, with the eye of a
man centuries ahead of his time, he wrote in his notes, “The moon has
every month a winter and a summer. And it has greater colds and greater
heats and its equinoxes are colder than ours.” He went further and
identified the elements existing on the moon such as “water, air, and
fire,” and described them and their functions as being like those on our
own earth. In so doing he recognized the existence of the moon as a
solid in space, reflecting the light of the sun—one of many “stars” in a
universe. With his acceptance of this concept he realized that the earth
could not be organic.


In May of 1504, the Signoria complained to Leonardo that there had been
no progress on the proposed paintings for their council chamber, even
though he had already been partially paid for them. Accordingly, he was
forced to sign a document that he must be finished by February of next
year or refund all monies paid him. As was his custom he had made many
preliminary drawings. Although he was well acquainted with horses he had
again researched their anatomy and actions. Pages of rearing, frightened
horses and men in combat covered his studio tables. On one of these
pages there are sketches of the heads of a lion, some horses and a
man—all with fierce expressions on their faces. Here Leonardo hinted at
the comparative anatomy of expression in man and animal that Darwin was
to write about almost four hundred years later.

But the paintings could wait, for now the Arno River was in spring
flood. The time had arrived to make the first attempts at diverting the
river into its new course. Leonardo was again in the field supervising
the work. There had been much opposition to Leonardo’s canal from both
the army captains and the Signoria. It was called a whim and a crazy
idea, but Piero Soderini and Niccolò Machiavelli were stubborn in their
defense of Leonardo’s plan and they overcame all opposition to it. And
indeed, the raising of the sluice gates was successful and the Arno
actually flowed into its new bed. The tensions in the camp and in the
Council of Florence were eased. The only sad person was Leonardo, for he
had just learned of the death of his father.

Leonardo felt the loss deeply. Outwardly, however, he only acknowledged
the death of his father at a distance. Not only had Leonardo and his
father drifted apart over the years, Piero left nothing to Leonardo in
his will. His father’s other children quarreled among themselves over
what money he did leave. Leonardo’s one friend in the family was Uncle
Francesco, who was still living in Vinci. When he heard of his brother’s
will, Francesco made out a will of his own and left everything to the
nephew he loved—Leonardo.

After having successfully diverted the Arno river, it was now necessary
for Leonardo to return to the painting commissioned by the Signoria for
its council chamber. But recently, Leonardo had suffered a rebuff in
this work. Originally he had been given the whole room to do but now the
opposite wall had been assigned to another man—Michelangelo Buonarroti.
Leonardo had first met the young Michelangelo when he helped to judge
the best location for Michelangelo’s monumental statue of David. The two
men were opposites in every way. Leonardo, fifty-two years old,
carefully dressed, cool and detached, was a man whose every action was
the result of a thoughtful and analytical mind. Michelangelo, twenty-six
years old, his clothes rumpled and covered with marble dust, was
passionate and moody—an impulsive youth totally dedicated to art. They
did not like each other, and now Leonardo was forced into a rivalry for
which he had no heart.

The duel between these two giants of art aroused the whole of Florence
and there was a constant stream of people watching them at work.
Michelangelo was given a studio in the hospital of Sant’ Onofrio and
Leonardo was working in the Papal Chamber in Santa Maria Novella. Among
the many people who came to watch Leonardo was a young man of nineteen.
He was already a pupil of Perugino and the experience of meeting and
learning from Leonardo was to influence him the rest of his life. His
name was Raffaello Sanzio—one of the great Renaissance painters of Italy
and known to us by the name of Raphael.

While Leonardo worked at Santa Maria Novella he had the opportunity of
continuing his studies in anatomy. Dissections at that time were
novelties and when one was performed the doors were thrown open to the
public. Leonardo must have attended the public dissections at the Church
of Santa Croce. Now at Santa Maria Novella there was a hospital, and
here Leonardo was able to continue his own dissections without
interruption. In a cool room below the hospital where bodies were kept
Leonardo worked late into the night. By the flickering lights of candles
and in the silence of the world about him he studied, drew, and wrote in
his notes of the wonders of the human body.

    [Illustration: _In a cool room below the hospital, Leonardo worked
    late into the night._]

He performed autopsies on people who had died natural deaths—a special
permission granted to him by the monks of the church, and among these
autopsies are the first written reports of some of the diseases that are
the causes of death. Arteriosclerosis, or stony growths in the blood
vessels, and pulmonary tuberculosis, a nut-like growth in the lung, are
among the discoveries Leonardo made in his lonely searches, although he
did not use these medical names for them.

Above all Leonardo was attracted to the function of the muscles,
especially those in the arms and legs. So faithfully, in fact, did he
record the origin and insertion of all the various muscles that these
drawings can be used as anatomical models today. Moreover, he believed
that a good drawing was worth pages of words describing human anatomy.
The muscles were rendered as cords so as to better understand their
function. He described this function as one of pulling instead of
pushing and he noted that for every muscle there is an opposing muscle.
When one contracts the other expands. For example, when you tighten the
biceps in your arm you can feel the looseness of the triceps, the muscle
on the opposite side.


As the end of the summer of 1504 approached, Leonardo’s dream of the
canal from Florence to the sea was destroyed. The summer had been hot
and without rain. The water in the canal dried up and the Arno river
returned to its original course. All the old arguments against the plan
were revived. The Florentine army captains rebelled against the job of
defending a useless project. Again Soderini and Machiavelli intervened.
After heated debates in the Council of Eighty, which had been called
into special session, Machiavelli himself was sent out to oversee the
work. It was brought almost to completion when in late October disaster
struck. The rains that had failed to come in summer fell from the
heavens in great cloudbursts. Storm after storm swept the valleys. The
workmen left and the soldiers were recalled. The Pisan army rushed in to
fill up the diggings and one final storm washed away the dream to
nothing but eroded mounds of dirt.

Leonardo buried his disappointment in other work. When the drawing for
the Battle of Anghiari was ready for transfer to the wall of the council
chamber, he had a special scaffolding made of his own invention which
worked on the principle of a pair of scissors standing on end, with a
long platform on top. As the legs were spread the scaffolding was
lowered and when they were pinched together it was raised. The wall had
been prepared with a special mixture which he hoped would bring out the
brilliance of his tempera colors. With several assistants who had been
assigned to him by the Signoria the violence of the Battle of Anghiari
was transferred to the wall and the actual painting was begun.

During the winter months Leonardo would relax from his work on the huge
painting and his dissections to roam the country around Florence. He
visited the slaughterhouses where the animals were killed and prepared
for market. Here he was able to examine the hearts of animals just
slaughtered and to note that the heart retained its action until the
body was almost cold. He made a glass model of the aorta (the main
artery leading from the heart) of an ox with which he could experiment
on the flow of the blood. He intended to add to it a glass tube for one
of the semilunar valves of the heart. He also experimented with a frog,
dissecting its brain, heart, and entrails and noted that it ceased to
twitch only when the spinal cord was severed. In his notes, he wrote,
“The frog instantly dies when the spinal cord is pierced; and previous
to this it lived without head, without heart or any bowels or intestines
or skin; and here therefore it would seem lies the foundation of
movement and life.” He was of course searching for the reasons that
muscles moved and from where the impulses originated.

One of Leonardo’s favorite places to visit was Fiesole where his uncle
Allessandro Amadori lived. Uncle Allessandro was the brother of
Leonardo’s first stepmother and, since he had loved her so much, he
likewise felt an affection for Allessandro. At Fiesole, which rises over
Florence in a steep ascent, Leonardo could watch the birds circling in
the air below him.

On these lofty heights, he would unfold his drawings of flying machines.
Leonardo had progressed now to a point where an actual flight was all
that was left. He had designed a sort of flying boat—a shell with wings
that moved up and down and he had introduced a tail like that of a bird.
He had noted that the tail of a bird acts as a rudder, a stabilizer and
a brake when landing.

But Leonardo’s most recent design was one that was called an
_ornithopter_. It consisted of a wooden frame, two huge wings like a
bat’s, a series of ropes and pulleys and a windlass, all planned with
the lightest of materials. The flyer, lying prone in the frame, his feet
in leather stirrups connected to the wings by pulleys, would move his
feet up and down to flap the wings while, at the same time, he operated
the windlass with his arms in order to guide the machine. Soon he hoped
to build this machine and try it out.

Meanwhile, Leonardo returned to his painting in the council chamber with
impatience, for spring was approaching and the time to finally realize
his dream of flying would be at hand. Aside from an assistant who had
tested the pedals and windlass, no one knew of his plan to actually put
his machine in the air.

    [Illustration: _The_ ornithopter, _one of Leonardo’s designs for a
    “flying machine.” By pumping his feet in the stirrups, the flyer
    could flap the device’s wings._]

Weeks passed and the painting was almost finished. The huge wall was
covered with plunging horses and embattled soldiers. The colors were
brilliant on the special mixture he had prepared for the wall—but they
were not drying as they should have. Something was wrong. To speed the
drying process, Leonardo had a special fire built in the room that
directed the heat onto the painting. Spectators were allowed to watch as
the waves of hot air rose against the wall. Then—disaster began slowly
with a small trickle of paint from the top! Before anybody could put out
the fire, the great figures and horses slowly melted down the wall in
shiny, sticky streaks of color. Leonardo fled the room in an agony of
shame.

With his own friends discouraged, the Signoria hostile, and the friends
of Michelangelo triumphant, Leonardo went back to Fiesole. He went back
with his secret dream of flight. The world would soon forget the Battle
of Anghiari—but the conquest of the air, if he could achieve it, would
live forever.

In the spring of 1506, from the slopes of Monte Cecero near Fiesole,
legend tells us that a great bird sailed into the air and disappeared.
No one knows whether Leonardo actually flew his machine or not but
Girolamo Cardano, the son of a friend of Leonardo, wrote, long after
Leonardo had died, “Leonardo da Vinci also attempted to fly, but he
failed. He was a fine painter.” Another dream had been shattered.



                                   11
                         _The Return to Milan_


Leonardo felt his fifty-four years that spring day in 1506. The
bitterness of his failures and the frustration of his dreams added
considerably to the weight of his years. All morning he had wasted in
argument with Soderini and the Signoria. If it had not been for the
letter from Charles d’Amboise, Viceroy of the King of France for Milan,
he would have felt like a beggar. Charles d’Amboise had been appointed
military governor of Milan by Louis XII ever since the French had
conquered that city and captured Duke Ludovico Sforza. But the authority
of the letter had finally won a grudging consent from Soderini. Leonardo
looked about him to see if he had forgotten anything and slowly climbed
onto his horse. He nodded to Salai, his apprentice, looked back to see
if his servant had the pack-horses ready, and started down the street
leading the small procession. He was going back to Milan.

Leonardo took out the letter and reread it. The words were respectful
and admiring—and in French. They requested the presence of “Maître
Leonard de Vinci” at the court of Charles d’Amboise, for purposes of
painting and other “diverse projects” for the King of France. The letter
restored a measure of confidence to Leonardo’s self-respect. Before
Leonardo left, Soderini had made him sign a letter in which Leonardo
promised to return to Florence within three months and to leave a
deposit of one hundred and fifty florins which would be held against his
return. It was signed, notarized and dated May 30, 1506. Nevertheless,
Leonardo had decided to accept the French envoy’s offer; moreover, he
looked forward to the prospect of returning to his vineyard at Porta
Vercellina and the understanding of a sympathetic patron.

Indeed, Charles d’Amboise turned out to be more than sympathetic. He
recognized Leonardo as a great artist; but even more, he was one of the
few patrons who could appreciate the magnitude of Leonardo’s scientific
and mechanical genius. In the court of Charles, Leonardo once more
enjoyed a time of peace and an assured income. The French
Vice-Chancellor of Milan, Geffroy Carles, who was second in command, was
also a distinguished scholar and a patron of the arts and natural
sciences. With the admiration and support of these two men and
especially with the distant backing of King Louis XII of France,
Leonardo’s dismal memories of Florence began to fade.

Leonardo’s three months’ allotted absence from Florence, however, were
soon past and a letter arrived from Soderini demanding either Leonardo’s
return or a forfeiture of the one hundred and fifty florins deposit. Now
a tug-of-war developed between the Viceroy of Milan and the governor of
Florence over Leonardo. The Signoria reminded Charles that Leonardo had
his work to complete, while Charles d’Amboise and Geffroy Carles
demanded an extension of time. One month more was granted. More letters
were exchanged until the affair became so heated that the King of France
himself intervened. In January of 1507 the French King informed Soderini
and the Signoria that Leonardo was “not to move from Milan until our
arrival.” Since Florence at this time was under the protection of the
French, such final authority silenced the Signoria. Shortly afterwards
Leonardo discharged his obligation to the Signoria by relinquishing the
one hundred and fifty florins, and he at last became free from the
demands of his native city.

On May 24, 1507 King Louis XII re-entered Milan with all the splendor
and color that France and the Dukedom of Milan could confer upon their
ruler. Knights in armor and the ladies of the courts followed the king
who rode in flowing white and gold under a canopy of blue decorated with
the lilies of France.

With such pomp and display in Milan, Leonardo was soon back at his old
occupation of designing pageants and tournaments. While some of the
people from the days of the Sforzas returned, not many remembered Duke
Ludovico, who was slowly dying in a French dungeon. Among the people
that Leonardo now met, there appeared Francesco de’ Melzi, a noble from
an old Milanese family, who entered Leonardo’s life at this time as a
pupil. Soon the young man became like a son to Leonardo. Of handsome
appearance, he had the sensitivity to appreciate the essential
loneliness of Leonardo and so, almost without realizing it, he filled a
gap in Leonardo’s life that was to last until the end of his days.

Yet, as Franceso de’ Melzi opened one door of Leonardo’s life another
door closed. He received word that his beloved uncle Francesco had died
at Vinci and that he had become the heir to his uncle’s property. No
sooner had this news been delivered when Leonardo was notified that
Giuliano, a son of Piero, and now a lawyer in his own right, was
contesting the will. All the frustrations of his life in Florence now
rose to an angry pitch and he set out once again for Florence to fight
for his own rights.

Wisely, Leonardo had armed himself with letters from his new,
influential patrons and even one from King Louis himself recommending,
“... we request that you will cause this dispute to be settled in the
best and briefest delivery of justice....” In August of that same
year—1507—Charles d’Amboise added his personal letter suggesting that
the king could not spare Leonardo too long from the court at Milan.

It was with the title of Painter and Engineer to the King of France that
Leonardo rode back to Florence to await the outcome of the judges in his
case. He went to stay with a sculptor friend, Giovanni Rustici, a man of
thirty-five and also an ex-student of Verrochio. They lived in a house
lent to Rustici by a wealthy scholar and patron named Piero Martelli.

Leonardo soon found that he and Rustici had much in common. Rustici,
too, collected the odds and ends of his journeys into the country.
Flying about the house were a tame eagle and a raven, while, at dinner,
a pet porcupine begged for food. Rustici, however, was a believer in
alchemy and magic. To practice these arts the young man devoted one room
to the strange mixtures which bubbled over flames as he attempted to
change base metals into gold, or to call upon the spirits to predict the
future.

Leonardo settled into the life of the house very quickly and even helped
his friend on an important sculpture commission. This was a group
composition of St. John between the Pharisee and the Levite for over the
doors of the baptistry. He also started to gather together his scattered
notes on all the subjects that he had written about, going through them
making corrections and erasing the repetitions. Possibly Leonardo was
considering the publication of all his material for he wrote, “Begun at
Florence in the house of Piero di Braccio Martelli, on the 22nd day of
March, 1508. This will be a collection without order, made up of many
sheets which I have copied here, hoping afterwards to arrange them in
order in their proper places according to the subjects of which they
treat....” This “collection without order” of almost forty years
extended into practically all branches of human knowledge, founded on
years of observation and experiment. Indeed, it was the magnificent
effort of one extraordinary mind to push back the curtains of ignorance
in order to let the light of natural truth shine through to mankind.

In addition, Leonardo returned to his studies of anatomy and comparative
anatomy. For this latter he made many beautiful drawings of the legs of
animals as compared to those of man. With them, Leonardo tried to
indicate man’s place in the natural order of the world. He pointed out
that our physical bodies are basically the same as those of animals, and
that the muscular and organic differences are those of function only.
For example, bird and man have the same chest muscles, called the
pectoralis. But the bird, in order to fly, has developed these into
powerful instruments of motion. Man, on the other hand, has learned to
stand and move in an upright position. He has developed the muscles of
the back, called the erectores spinae, and those of the buttocks to hold
him erect. Leonardo intended to enlarge upon his studies of comparative
anatomy to include all living creatures, even the insects.

Meanwhile, the Viceroy of Milan was becoming impatient for Leonardo’s
return. The judgment against his half-brothers had been settled in
Leonardo’s favor, and he hastened back to Milan. By the summer of 1508
he was once more in the routine of the court’s activities. King Louis
had granted Leonardo a regular allowance and it was the first time he
had enjoyed such a long freedom from the concerns of earning a living.
With these steady payments Leonardo now had the leisure and support to
pursue his own multitude of interests.

As his notes began to take shape and he thought of printing them, it was
natural for the inventive Leonardo to design his own printing press. It
is one of the earliest such designs on record. Because the carrying bed
which held the type and the paper was automatically adjusted to the
handlebar, the press could be operated by one man. Besides his notes
Leonardo also considered printing a work by Roger Bacon, the thirteenth
century English scientist.

This project for printing his own books, however, was never realized by
Leonardo. Lately, he had received a commission which took him back in
memory to the days of Ludovico. The subject was Marshal Gian Giacomo
Trivulzio, a soldier-of-fortune. Originally this man was a loyal
commander of Galeazzo Sforza’s but when Ludovico came to power he had
had Trivulzio banished from Milan. Embittered, Trivulzio had become a
stubborn enemy of Ludovico from that time on, serving under any banner
that marched against the house of Sforza. A stocky, square-faced man,
his body was covered with the scars of many battles. He had been
fighting with the French ever since the time Ludovico had betrayed
Charles VIII. Trivulzio had seen the great monument that Leonardo had
modeled and, although it was riddled by French arrows and damaged by
wind and rain, the Marshal was impressed and wished for a similar
memorial to himself.

Leonardo set to work immediately. His past experience with the Sforza
monument was now to his advantage. This time there was no need for
experimenting. He knew how much material he needed and the approximate
cost of everything including the casting. He submitted an estimate of
three thousand and forty—six ducats for the completed work, one hundred
of which would go to Leonardo. The sum was acceptable to Trivulzio and
Leonardo began his preliminary studies.

As he gathered the material for this new equestrian statue, Leonardo and
the French Viceroy Charles d’Amboise became interested in the further
canalization of the plains of Lombardy. The use of canals and locks had
been in practice for roughly a hundred years and around Milan there were
already some fifty miles of canals and about twenty-five locks. Leonardo
started another survey of the area. In his imagination, he envisioned a
vast hydraulic engineering project.

On September 12, 1508 Leonardo announced in his notes the beginning of a
book on the nature of water. He had decided to separate this book from
the one on hydraulics because it was necessary to separate theory and
practice. His pages treating the science of hydraulics, or the practical
applications of water power, had reached to “forty books of benefits.”
By the spring of 1509 he had expanded his notes on the nature of water
to include the greatest wave to the smallest raindrop.

Concerning the practical applications of water power, Leonardo put forth
many designs for new locks. He introduced new methods of raising the
gates by windlasses and chains which could easily be set in motion by
one man. But most important is Leonardo’s discovery of the use of
centrifugal force for draining marshes—the ancestor of the centrifugal
pump. When you rapidly rotate a stick in a pail of water, the water
spins in a spiral rising on the sides, and, if you rotate the stick fast
enough it bares the bottom of the pail. When you remove the stick
suddenly, the water continues to whirl as it slowly subsides.

This is basically the same principle Leonardo used to raise the water
from a marsh to a level above the sea so that it could be drained away.

The centrifugal pump was also used with a hydraulic screw which
converted water power to mechanical power. The force of a stream of
water was injected into the base of a vertical cylinder. In the base of
this cylinder was a six-bladed propeller mounted on a vertical shaft.
The force of the water turned the screw and at the same time the water
was forced to rise in the cylinder to an outlet above. The turning
propeller revolved the vertical shaft. This shaft, emerging from the top
of the cylinder, turned a cogged wheel. This wheel was joined to another
cogged wheel mounted on a horizontal shaft, thus providing the
mechanical power. Not only is this the forerunner of the turbine, but
the use of the propeller, itself, for propulsion in water, was a new
idea not to be thought of again until the eighteenth century. For
certain types of hydraulic pumps he conceived of the cone-headed mitre
valve still in use today.

Leonardo, besides studying the practical applications of water power,
explored the very nature of water itself. In his proposed books on this
subject he intended to examine why clouds and fog form, why rain falls
and the raindrop itself—even how the raindrop is held together. He
understood the nature of capillary attraction, which holds the raindrop
together, and his notes show us that he was exploring the science of
hydrostatics which relates to the pressure and equilibrium of liquids in
general.

Now that Leonardo had a steady income and the relief from meeting
painting commissions by fixed dates, he was free to explore his other
favorite avenues of knowledge. It seemed that his ever-active mind could
never stop roaming over the whole field of scientific knowledge. He
continued with his early interests—the nature and movement of air,
astronomy and geometry. He was also still concerned with movement and
weight, for he set down in his notes, “The thing which moves will be so
much the more difficult to stop as it is of greater weight.” This is a
hint at a principle formulated by Isaac Newton almost two hundred years
later in his First Law of Motion—the law concerning inertia. For
example, the motion of an arrow shot into the air maintains itself in
flight so long as the influence of the initial force is maintained in
it.

    [Illustration: _Da Vinci’s cone-headed mitre valve for use in a
    hydraulic pump._]

On a note dated April 28, 1509 he wrote, “Having for a long time sought
to square the angle of two curved sides ... I have solved the
proposition at ten o’clock on the evening of Sunday.” As always,
Leonardo was deeply involved in the study of mathematics. Too deep
perhaps to recognize the new rumblings of war.

Louis XII, still pursuing his campaign in northern Italy, had again
arrived in Milan amid the salutes of the French artillery. Following his
personal banner of a gold porcupine on a white field, he had come back
prepared to do battle with the Venetians whose power, as it diminished
in the east, was extending westward into Italy. Alarmed at this Venetian
expansion, the French King had allied himself with Pope Julius II and
the powers of Europe to form the League of Cambrai to push back this
threat. Charles d’Amboise, the French Viceroy, had already taken to the
field and at the castle of Cassano, overlooking the Adda river near
Milan, he awaited the arrival of his king.

By the end of May, Leonardo was in the saddle once more. Surrounded by
the best knights of France and the nobles of Milan, he personally
accompanied the French King as military engineer to the meeting with the
Viceroy of Milan at Cassano.

During the next three months, through the battles and defeat of the
Venetians at Aquadello where sixteen thousand dead were left on the
field, and the siege of Caravaggio and the capture of Peschiera,
Leonardo served as military consultant and map maker. More than ever his
eye was attracted to the possibilities of utilizing the many rivers they
crossed both for warfare and commerce. He envisioned making the Adda
river navigable from Milan to Lake Como. During this time, he devised
not only a revolving bridge but even one of two layers in a single
span—the upper level for pedestrians and the lower one for vehicles.

By July, Leonardo had returned with the king and the French army to
Milan. Here was planned a great celebration of the French victory over
the Venetians. In front of the cathedral, to the delight of the hundreds
of spectators, Leonardo devised a mechanical lion scaring a dragon out
of an artificial lake into the beak of a cock which picked the dragon’s
eyes out. After the festivities Leonardo returned to his everyday work.
In time, he had a thriving workshop and as he became more and more
preoccupied with his scientific explorations, his art commissions were
turned over to his assistants. He did continue, however, to work on the
plans for Marshal Trivulzio’s monument and in his preparatory work for
this assignment he expanded his notes and drawings of comparative
anatomy.

This renewed interest in anatomy led him to attend a lecture in the
winter of 1509. The lecturer was Marcantonio della Torre, a young man in
his late twenties and one of the best-known anatomists of the times. He
had been a professor at the University of Padua, but this city had
fallen into the hands of the Venetians. Marcantonio was forced to flee
Padua and had settled at Pavia. The two men, when they met, recognized
in each other a devotion to science and they began a professional
collaboration that grew into a friendship. Leonardo now developed his
anatomy studies to the point where he is today recognized as the
foremost medical anatomist of the Renaissance.

Returning to his dissections, Leonardo now proceeded to explore the
heart and system of veins in the human body. His drawings of the heart
are nearly perfect. Indeed, he was probably the first to discover the
endocardium membrane that sheathes the valves and sinews of the heart.
Also, he pictured and described the moderator band, “the first cause of
the motion of the heart.” His work on this organ led him to the doorstep
of discovering the circulation of the blood—later to be carried out by
William Harvey in the seventeenth century.

Further, Leonardo was the first to accurately draw a representation of
the _foetus_, or unborn child, in the womb of its mother, writing in his
notes that, “we conclude therefore, that a single soul governs the
bodies and nourishes the two.” In addition, he drew a remarkable picture
of the female figure and for the first time accurately placed her
organic structure. In his notes, he also pointed the way to the laws
governing metabolism when he wrote, “The body of anything whatsoever
that receives nourishment continually dies and is continually
renewed....” By pouring wax into a hole in the skull he made the first
casts of the ventricles of the brain. Several hundred years were to pass
before this method was rediscovered.

As Leonardo’s work progressed, his admiration for the complexity of the
human body grew. Many times in the middle of explaining a section of
anatomy he inserted a sentence or two of wonder or praise at the
magnificent creation that is the human being. Indeed, these drawings and
notes represent the sum of many, many dissections; moreover, Leonardo
had to work under conditions that placed many obstacles in his path—the
crude lights and instruments, the difficulties of obtaining corpses and,
above all, the opposition of the superstitious and ignorant.

The following year Leonardo entered in his notes, “This winter of the
year 1510 I look to finish all this anatomy.” And yet, however sincerely
he might express such a wish, Leonardo was a person who was literally
never “finished.” The scientific and artistic tasks he had chosen for
himself were clearly beyond the limits of any one man. Besides, the
pressures of the outside world were once more threatening the peace and
quiet of his home and work.

Pope Julius II became increasingly fearful of the French victories over
the Venetians. Secretly, he concluded a peace with Venice and, allying
himself with his former enemy, he now turned against the French. When
the conflict continued, Charles d’Amboise, the patron of Leonardo, was
killed at the battle of Correggio. He was replaced by a new French
Viceroy, Gaston de Foix. Although the Pope now hired Swiss mercenaries,
this invasion from the North was defeated by the young Gaston. Not to be
outdone, the Pope then brought in Spanish troops.

In the ensuing bloody battle at Ravenna, the French completely defeated
the armies of the Pope and Spain, despite their use of battle-cars armed
with razor-sharp sickles on their wheels—strangely like the early
inventions that Leonardo designed for Lorenzo de’ Medici! Although the
French were victorious, they lost their brilliant young leader, Gaston
de Foix, and with him they lost their heart. As a result, they were soon
disorganized. The Pope’s armies renewed their attacks, and the French
began a long retreat.

Once again the plague infested Milan and Leonardo’s friend, Marcantonio
della Torre, died of it. After some futile attempts at recovery, the
French fled across the Alps and with them went Marshal Trivulzio. Milan
was left temporarily under the martial rule of the Swiss, and Leonardo
with only his few apprentices was left again without a patron.

Tired and prematurely old at sixty-one, Leonardo resignedly gathered his
possessions together once more and with Francesco de’ Melzi and four of
his loyal pupils, he turned his back on Milan for the last time. The
date was September 29, 1513. Their destination was Rome.



                                   12
                                 _Rome_


“Name?”

“Leonardo da Vinci.”

“Where from and where are you staying?”

“We are coming from Milan by way of Florence. I have quarters being
prepared for me at the Belvedere in the Vatican—by order of the Pope.
Now, young man, let us pass.”

The guard at the Porta del Popolo changed his manner. He dropped his
halberd and motioned to the other guards to let the riders through. He
touched his helmet roughly and with a grin he said,

“I’m sorry, Sire—but you know how it is. All these people—there’s bound
to be them that we don’t want here. Go ahead, your Excellency. Make way
there!”

With these words he laid his spear against a jostling group of
broad-hatted pilgrims blocking the entrance to the city of Rome.

Leonardo heeled his horse and with Francesco de’ Melzi at his side,
followed by his servant and students, pushed past the crowd at the gate.
To the left rose the Pincio hill with its stately pines where, in the
days of Imperial Rome, Lucullus had walked in his gardens. But Leonardo
had no time to look about. It was a damp December day, and rain
threatened from the gray skies. He was tired, and as Francesco glanced
at him he could see Leonardo pull his cape around him with a little
shiver as the chill wind stirred the long, graying hair on his
shoulders. They made their way through the crowded, noisy city. They
crossed the Tiber and rode past Castel’ Sant’ Angelo, the papal fortress
built on the tomb of Emperor Hadrian. After another inspection by the
Swiss guards in beribboned uniforms of white, green and gold under their
shining breastplates, they entered the walls of the Vatican. That
evening after he had settled himself in the Belvedere apartments and
dinner had been eaten, Leonardo, gazing into the embers of the fire,
looked back over his new stroke of fortune.

The Medicis had returned to power. Pope Julius II had died, and Giovanni
de’ Medici, son of Lorenzo, had become Pope Leo X at the age of
thirty-seven. With his election to the head of the Christian world, the
Republic of Florence became a city of the Medicis once more and Leonardo
had received an appointment in Rome. Giuliano de’ Medici, Pope Leo’s
favorite younger brother, in his new rise to power and wealth, became
Leonardo’s patron. The two must have met sometime during the Medici’s
exile. Leonardo was given the apartments in the Vatican and a salary of
thirty-three ducats (approximately eighty-five dollars) a month and a
workshop was fitted for him and his pupils. He was also assigned an
exclusive German assistant named Georg.

The Pope’s court in the Vatican was like the Medici court in the
Florence of Leonardo’s youth—multiplied by hundreds. Leo X saw himself
as the center of the artistic world, and being a man of luxurious tastes
with the wealth of the church behind him, the Vatican was soon filled
with a mixture of the wise and foolish. Pompous classic-quoters,
third-rate poets and clowns mixed with the world’s scholars and
statesmen. The two greatest artists were Bramante, the architect and
friend of Leonardo’s first years in Milan, and Bramante’s pupil Raphael,
the painter.

Bramante was busy building the new church of St. Peter’s and, as the
architect of this favorite project of the Popes, he was sole master of
the Roman art world. Raphael, as his protege, was the recipient of the
better painting commissions in Rome. The elderly Bramante and the
thirty-year-old assistant were a famous pair in the Rome of 1513.
Equally as famous, however, was Michelangelo; he was still living in
Rome, but was without patronage after Julius II’s death. Leonardo’s old
rival had scored his triumph with his extraordinary paintings in the
Sistine Chapel.

Although the young Raphael, who owed so much to the example of Leonardo,
now rode through the streets as a wealthy nobleman, Leonardo himself
received no great commissions. While Pope Leo was indulgent of his
brother’s whims he himself had no use for this tall, serious old man who
roamed the shaded walks of the Vatican poking at the strange plants in
the botanical garden or making drawings of the foreign animals in the
private zoo. In reality, Leonardo’s patron, Giuliano de’ Medici was a
weak man. He played at being a patron but, like his brother the Pope, he
lacked the force and decision of his famous father Lorenzo.
Nevertheless, he did give Leonardo one small commission for a picture.
Immediately Leonardo, excited by the exotic plants in the Vatican
gardens, commenced to experiment with them to find a resin to make a
varnish with which to cover the future painting. Pope Leo made fun of
him exclaiming, to the delight of his court, “This man will never get
anything done, he thinks of the end before the beginning.”

This ridicule by the Pope made Leonardo a joke to many in the circles of
the Vatican who were a little afraid of this strange man with the
searching eyes. Leonardo also suffered the humiliations of a man who did
not conform to the fashions of his day. His knowledge of Latin, for
example, was weak and although he could read it with the help of a
dictionary he could not speak it. And, among the people who surrounded
the Pope, Latin was the only language allowed. Prizes of great sums of
money and important positions were often granted on the strength of an
improvised speech in Latin (with many quotations from the classical
authors) or a flattering Latin verse. Faced with such setbacks and
ridicule, Leonardo—not surprisingly—began to withdraw into himself.

And yet, Leonardo refused to remain idle—he had to work. The need for
mirrors in the vast halls and rooms of the papal palace was great.
Leonardo turned his mechanical skill to redesigning and improving
methods of making them, and even inventing his own machines for the
grinding of the glass. Also, for Giuliano, who dabbled in alchemy and
magic, he made distorting mirrors and burning lenses. In addition,
Leonardo invented a machine which could be run hydraulically for
producing long strips of copper of equal width for use in soldering the
mirrors.

But, with the making of these mirrors, Leonardo began to run into
trouble with his German assistant, Georg. The boy was a loafer; he spoke
little Italian and took every opportunity to spend his days with his
countrymen in the Swiss guard. Leonardo tried to alter the situation by
suggesting that the boy have his meals with him at his worktable, thus
giving Georg a better chance to learn the language. This however did not
appeal to him. Then, because Leonardo’s inventions were so
extraordinary, he began to give away the secrets of their mechanisms to
Johannes the mirror-maker, another German, who had been replaced by
Leonardo in the favors of Giuliano. This naturally made Johannes jealous
of Leonardo. Georg gossiped, too, and told stories about the old,
eccentric man who lived like a miser in the midst of all the luxury and
who drew crazy circles on pages of paper.

These “crazy circles” were geometric exercises that had fascinated
Leonardo from the time he had wandered across Italy with Fra Luca
Pacioli. Pacioli’s book _De Divina Proportione_, containing sixty
illustrations from designs of Leonardo, had been published in Venice in
1509. Leonardo intended to entitle these geometric exercises _De Ludo
Geometrico_. In geometry a lune is a crescent-shaped figure bounded by
two intersecting arcs of circles on a plane or a sphere. Leonardo drew
pages of these lunes and then proceeded to transform their curvilinear
figures into squares of equal area. He also reviewed Archimedes’ method
of squaring a circle and developed it into a variety of ways for cubing
spheres and cylinders.

He returned as well to formulating theories of friction. He wrote in his
notes, “the tallest wheel is the easiest to pull”—for example, a big
wheel turning at the same speed as a smaller one has less friction to
overcome because it makes less revolutions. His experiments in friction
predated men like Amontons and Coulomb by two and three centuries. He
established a formula for the building arch which he described as “a
strength caused by two weaknesses”—if one half of an arch is removed,
the other half collapses. They support and give strength to each other.
In addition, Leonardo determined, before Galileo, the center of gravity
of any pyramid and of a tetrahedral, or four-sided body.

As the days went by and he waited for commissions to come, Leonardo took
to wandering about the streets of Rome. He stood in the half-buried
Forum of the Caesars surrounded by grazing sheep and grunting pigs.
Wooden shacks where crude cartwheels were made and where the marble from
the ancient temples was cut and sold, were built against the sides of
crumbling ruins. The old triumphal arches, now overgrown with creepers,
were boarded into towers and cattle were penned between the shafts of
columns that once supported the grandeur of temple roofs. Here and there
a classical scholar would be sketching or writing from the worn, Latin
inscriptions on a marble slab tilted crazily from the ground where it
had fallen hundreds of years ago. Goats wandered on the Palatine hill,
once the home of Emperors, and the great baths of the Emperor Diocletian
were now a deer park and a hunting ground for royalty.

During the course of these wanderings, Leonardo became interested in the
primitive methods of carpentry. Such things as screws, for example, were
rare. Those that were used were either made of wood or, if of metal, by
goldsmiths laboriously making each one by hand, soldering wire around a
pin and another wire into the hole to hold the screw. Sometimes they
were made by filing pieces of metal individually. All these methods were
time-consuming and costly.

Leonardo had thought of this problem before, and now he concentrated on
perfecting his ideas about it. Previously, he had thought of casting the
metal in wooden molds and then turning the metal on thread-cutters. The
designs he finally drew in careful detail, however, are essentially the
methods used today. The new machines did with a few turns of a handle
and adjustments of a few cogged wheels what it took one man many hours
to perform. He also drew designs for a mechanical plane and a machine
for drawing wire that worked by water power.

Leonardo now lived and worked in the Belvedere of the Vatican—more a man
on exhibition than an active participant in the great artistic
activities taking place around him. True, he received his thirty-three
ducats a month, but Michelangelo had been paid three thousand for his
work in the Sistine Chapel, while Raphael had earned twelve thousand for
each room he painted in the Vatican.

    [Illustration: _Leonardo became interested in various methods of
    carpentry._]

Thus Leonardo drifted farther and farther away from his painting. This,
in itself, caused people to talk in the papal city. For he had earned
fame as a painter, but his passion for science was regarded as strange
and whimsical. Occasionally, he did receive a small commission from the
workshop of Raphael, yet these were like the crumbs from a rich man’s
table.

Even the toys Leonardo made at this period for the amusement of his
patrons were looked upon as somewhat weird. For example, he would take
small pieces of wax and mold them into strange little animals and then
inflate them so that they floated in the air in front of a startled
guest. Once he caught a curious lizard in the garden and spent hours
putting scales all over the tiny body, attached to it a little beard and
horns, then let it out from a box at a banquet. The guests jumped back
with fear and the women became hysterical.

One of Leonardo’s jokes that has been passed down in accounts of his
life at this period must have created quite a sensation. He showed the
company the cleaned entrails of a sheep resting on the palm of his hand.
After telling them to wait and watch he took the entrails in another
room and with a bellows inflated them with warm air. As the entrails
filled with air they expanded and extended. They crept into the room
where the company waited. Slowly they grew and grew until they began to
fill the room. The guests overturned their chairs in their hurry to get
out of the way of this shapeless, translucent creature. Then Leonardo
appeared, the air-filled entrails giving way before him, and said:

“Sires, this is but an example and symbol of virtue. As you can see, the
smallest virtue is capable of the greatest growth.”

The guests laughed, but it was an uncomfortable laugh. Thus another
story was added to the legend of Leonardo as an odd old man.

Leonardo, whose work—particularly his anatomical studies—had constantly
been interrupted by the fortunes of war, had found another hospital in
Rome where he could continue these studies. This time it was his
intention to write a treatise on speech. He dissected and drew the
anatomy of the larynx (the voice box), the vocal cords and the trachea
(the air passage to the lungs), and all the muscles that control the
movements of the tongue and the lips. If you pronounce each letter of
the alphabet you will feel these muscles of the lips, especially with
the letters “o,” “p,” and “f.” Carefully he noted how the air vibrations
from the trachea form themselves into vowels and consonants, and he drew
the membrane which, when air is pressed against it, makes the sound
“aah.”

At this same time he was also busy finishing a treatise on painting
which he had begun when he was working on the “Last Supper” for Ludovico
Sforza. But it was for his knowledge of military engineering that he was
sent to the city of Parma by the Pope on September 25, 1514. Here he
stayed at the Bell Inn while examining the fortifications and other
defenses of the city.

Leonardo’s patron, Giuliano de’ Medici, had been appointed governor of
this particular area and, since Pope Leo X was fearful of two powerful
countries, France and Spain, he was preparing the papal territory
against possible invasion. Another fear of the Pope—and indeed of
everybody in Rome—was malaria, the disease carried by the mosquitoes
that bred in the Pontine marshes west and southwest of the city. At that
time, however, no one knew the cause was mosquitoes; rather, they
thought it was the bad air from the marshes.

As Leonardo had already been effective in draining the pestilential
marshes of Piombino for Cesare Borgia and, later, those around Milan for
Charles d’Amboise, he was assigned the same task for the Pontine
marshes. He surveyed the entire area to the sea and made another
extraordinary aerial type map. His recommendations included draining the
entire area, enlarging and regulating the Martino river and cutting an
extra outlet from the river Livoli to the sea. These plans were adopted
some years later and parts of the marshes were drained successfully,
yielding new land for the cultivation of crops.

By December of 1514 Leonardo had finished his treatise on speech and,
possibly in an effort to attract the attention of the Pope, he submitted
it to the Privy-Chamberlain, Battista dell’Aquila. As Pope Leo was
surrounded by an army of secretaries and assistants who passed on
everything submitted, this manuscript with its beautiful drawings was
mislaid and lost and only a few notes and sketches remain.

The continual discouragement of his life in Rome was offset by a visit
from his half-brother, Giuliano, around Christmas. Leonardo was held in
esteem by his family despite the quarrel over his father’s and his uncle
Francesco’s will, and his half-brothers were pleased to tell of their
famous relative who lived in the Belvedere as guest of the Medicis. Yet
they knew little of Leonardo’s scientific dreams and his lack of
recognition in the papal city.

Often, Leonardo’s greatest comfort was to return to his notes. The
challenge of geometry and the mysteries of the movement of air and water
kept him from brooding about his lonely life. Francesco de’ Melzi,
Leonardo’s young friend, had more and more taken over the practical
responsibilities of his everyday life. Except for his workshop, where
the troublesome Georg worked at the making of mirrors, and an occasional
small commission for a painting, Leonardo was free to study.

In addition to his geometrical investigations, Leonardo now experimented
with the science of _statics_ (objects that are stationary), and
_dynamics_ (objects in motion). One of his most important discoveries in
the science of mechanics came about during this period. Concerning the
division of weight, he wrote, “There are three conditions of gravity of
which the one is its simple natural gravity, the second is its
accidental gravity, the third the friction produced by it. But the
natural weight is in itself unchangeable, the accidental which is joined
to it is of infinite force, and the friction varies according to the
places wherein it occurs, namely rough or smooth places.” Thus he
realized and formulated what composes the movement of an object. He
found that movement is the result of separate forces acting upon the
object from different directions, as for example, the initial push, the
pull of gravity and the resistance of friction. And, before Galileo,
Leonardo further experimented with objects dropped from a height. As the
result of repeated experiments, he noted that the fall was being
affected by the earth’s rotation. That is, the object dropped always
fell in a slight eastward direction rather than vertically downward—a
fact later proved conclusively by Isaac Newton and Robert Hooke in the
next century.

He also became fascinated with spiral motion, such as is found in a
spinning top or in a whirlpool of water. Because of his interest in
_hydrodynamics_, or the movement of water, he began to sketch imaginary
“Deluge compositions.” These were drawings showing the world—probably
inspired by the Bible—in a chaos of wind and floods. They were based on
his years of scientific research. Indeed, his drawings of actual
whirlpools are still among the greatest of his scientific art. Today,
with all the latest technical aids, such as dusting a whirlpool with
powdered rosin and then photographing it, an accurate three-dimensional
picture is impossible. Yet Leonardo, by sheer observation and analysis
coupled with his genius for drawing, could reproduce the complicated
shape of whirling water.

In the relatedness of his explorations of water, air and movement, and
weight, he worked out the similarity between the laws of equilibrium
controlling solids and liquids. The equation between the motive force
and resistance that makes for equilibrium or balance in solids can be
compared to the equation between the upward pressure of liquids and the
downward pressure exerted on them.

Far into the night Leonardo worked on his papers. He tired more easily
now, and his eyes had grown weaker. To provide the increase in light
that his failing eyesight demanded, he had improved on his original oil
lamp by making the wick rise as the oil was burned away, and he had
extra lamps fitted to the ceiling.

On January 9, 1515 Leonardo wrote in his notes, “Il Magnifico Giuliano
de’ Medici set out on the ninth day of January 1515 at daybreak from
Rome, to go and marry a wife in Savoy. And on that day came the news of
the death of the King of France (Louis XII).” This meant that his new
patron had left and his old patron had died. Leonardo’s note was a sad
one and perhaps he felt, in the departure of his patron, more alone than
ever in the crowded life of the Vatican. Giuliano, on the urging of his
brother, was marrying Philiberta of Savoy, in an effort to strengthen
the prestige of the Medici. Louis XII, before he died, had formed a
league against Spain, and with the marriage of the Pope’s brother to a
noble house of France, the league would be strengthened by keeping the
Pope on the side of France. Actually Pope Leo was playing both sides,
for at the time he was also friendly with Spain.


Shortly after Giuliano’s departure from Rome, Leonardo fell ill,
presumably from a mild heart attack complicated by a touch of malarial
fever. The doctor had been called. It was a warning, the doctor told
Francesco de’ Melzi, and Leonardo must remain quiet for quite awhile.

By the end of the winter Leonardo was back on his feet and apparently
feeling completely well again. Giuliano himself had fallen ill about the
same time and the news that he had recovered and was finally returning
to Rome cheered Leonardo. He sat down and wrote a long letter to his
patron expressing his joy. This letter also included a long list of
complaints against Georg and Johannes. Georg was now using his room in
Leonardo’s apartment to do work for others. He lied to Leonardo and flew
into such a rage when he was questioned that no one could go near him.
Moreover, Johannes, the mirror-maker, was now moving back into the
Vatican and turning out mirrors for everyone, even using Georg’s room as
his own workroom. Johannes boasted of his skill and told everybody that
Leonardo did not know what he was doing. Thus, it was not surprising
that Leonardo, in his long complaint, was taking out the anger and
frustration he felt against all the injustices of his life in Rome.

But by summer Leonardo was again employed as a military engineer.
Francis I had succeeded to the throne of France. The new French King was
anxious to secure his lost title to the Dukedom of Milan and was
preparing another invasion of Italy. Pope Leo X, still trying to play
both sides at once, was making secret agreements with Francis while at
the same time joining the King of Spain, Milan, Genoa, and the Swiss in
an alliance against France. Consequently, he sent Leonardo out to
inspect the fortifications of Civitavecchia, a city on the Tyrrhenian
coast not too far from Rome. When, in August, Francis I crossed into
Italy with an army of thirty-five thousand men including Marshal
Trivulzio, the Pope ordered his brother, Giuliano, to take command of
the papal forces. On the way to assume this command, Giuliano fell ill
and collapsed. His sickness this time was soon to be fatal.

Leonardo returned to Rome with his survey of Civitavecchia, where he
immediately learned of his patron’s latest illness. Perhaps realizing
that Giuliano was fatally ill, Leonardo made a desperate effort to gain
the recognition he felt should be his. He entered the competition for a
new façade of San Lorenzo in Florence. Among the other competitors was
Michelangelo, his younger and yet oldest rival.

In October of 1515, Francis I had recaptured Milan and by Christmas was
in Rome. Leonardo may have met the new King of France in Bologna where
Pope Leo X had personally traveled in order to settle a peace treaty
with France. Certainly it is known that he attended Francis’ court in
Rome. Leonardo’s name was well respected in French circles and, as
Francis had already admired the pictures by Leonardo, the meeting was a
happy occasion for them both. Indeed, the recognition that Leonardo had
sought in his native land was never as great as that accorded to him by
the French.

As Francis I prepared to leave for France in January he must have
offered Leonardo a position at his court. While he still hoped that
Giuliano de’ Medici would recover from his illness and return to Rome,
Francis’ offer gave him support in the knowledge that he had a powerful,
new friend.

March of 1516 brought the first of three events that were to change the
course of Leonardo’s last years. Giuliano de’ Medici died, leaving
Leonardo not only without a patron, but without a friend in the Vatican.
Now sixty-four years old, he was reluctant to leave his comfortable
quarters in the Belvedere with its workshop and pleasant gardens.
Besides, deep within himself, he felt that Rome could still offer him
the fame that had always escaped him.

Spring ripened into summer and the second event occurred. The
competition for the new façade of San Lorenzo in Florence was won by
Michelangelo. To Leonardo the news was a blow. The success of his old
rival weakened his position in the Vatican even further and added to the
growing hostility he had felt in the people surrounding the Pope.

The third event was the sum of many small events. Georg and his friend
Johannes, in their jealousy, had spread much gossip about Leonardo in
court circles. They now took advantage of Giuliano’s death to circulate
stories about Leonardo’s dissections of bodies in the hospital. These
were added to vicious gossip that Leonardo was pro-French. This news
eventually reached Pope Leo X. The Pope himself was perfectly aware of
the practice of dissection and, personally, he had turned his eyes the
other way. However, as dissection was contrary to Church doctrine, an
official complaint to the head of the Church could not be ignored. The
Pope used it as an excuse to be rid of this tiresome old man whom he had
tolerated only for his brother’s sake. Leonardo was abandoned.

The year 1516 was drawing to a close. Leonardo had decided to seek the
patronage offered him by Francis I. So he and Francesco de’ Melzi, his
loyal young friend, left Rome for the long journey into France. As he
left his native land for the last time, Leonardo looked back over his
years—from the silver lute that had sent him to Milan, to the death of
Giuliano, to the final rejection of Pope Leo X. Remembering how Lorenzo
de’ Medici had sent him to Ludovico so many years before, Leonardo
thought to himself with great sadness, “The Medici created and destroyed
me.”



                                   13
                            _The Last Years_


Leonardo looked around from where he was leaning on the parapet of the
Chateau d’Amboise to watch a group of young lords and ladies playing
croquet on the emerald-green lawn. The click of the mallets and balls
was mingled with the shouts and laughter of the young people. It was
late afternoon in May and although the sun was warm the breeze from the
west was chilly. Leonardo looked down again from the sheer height of the
castle wall across the wide sweep of the Loire river and the valley
extending as far as the eye could see. Swallows were swooping low over
the banks below and the wind carried their shrilling cries up to him.
The forested islands and sandbars interrupted the steady flow of the
river and Leonardo could see the reflections sway in the current. He had
been studying the river but he realized that his aging eyes were not up
to the task of concentrating for long. The wind made them water, so he
turned away and started back to his home.

There was much that was familiar in the castle at Amboise. The thick,
high walls and round towers and especially the graceful, lacy spires of
the king’s residence brought back much that he had known in his native
land. The gardens had been planted by Italians—there were orange trees
and even a mulberry tree from his beloved plains of Lombardy. The king’s
residence and chapel had been constructed and the decorations carved in
stone by Italian artisans. Leonardo could stop and talk in his native
tongue with many of the men employed by the king. Since the time of
Charles VIII, the French had brought in the latest Renaissance styles
from Italy. Leonardo’s steps took him back from the castle grounds and
down a path with a hand-railing. The steep roofs of the town of Amboise
with their chimneys could be seen below him. The path led to a small
manor house, like a miniature castle with sharp spires and lacy,
carved-stone gables that was set in green lawns and gravel paths.

The Manoir de Cloux, as Leonardo’s house was called, had been a hunting
lodge for Francis I, but when Leonardo had arrived he gave the house to
Leonardo for his home. Francis, in his admiration for this great man,
also gave him seven hundred crowns a year, together with a pension of
four hundred for Francesco de’ Melzi.

    [Illustration: _Leonardo at Chateau d’Amboise on the Loire._]

The long journey from Rome had left Leonardo tired and weak and he had
fallen ill again shortly after his arrival. This time the attack was
more serious and had left him with his right hand permanently crippled.
He looked at it now as he opened the door to his room. “Another
warning,” he thought, “and there’s still so much to do.”

The young, robust King Francis was everywhere at once. He gloried in
knightly tournaments, hunts, and sports of all kinds. Always restless,
he might appear at any place unannounced. Frequently there would be a
clamor at the gates of Leonardo’s home and the king would ride in with
one or two of his nobles. With a great jingling of spurs he would bound
up the stairs of the manor house calling for Leonardo. He delighted in
long talks with the old man, and would listen respectfully as Leonardo,
his deep-set eyes brooding over his notes, would demonstrate some
scientific point on a blank sheet of paper.

At this time, Leonardo was engaged on three projects which demanded his
immediate attention. One was the entertainment for a banquet that
Francis was giving for his sister, Marguerite de Valois, and her
husband. Another was a new design for the king’s castle at Amboise, and
the third was a design for making a navigable waterway from Amboise to
Romorantin. Although these three projects were the main ones that
occupied Leonardo’s time, there was always the supervising of his
pupils’ painting on the walls in the little chapel of the manor house,
his own work on a painting of St. John the Baptist, and the continual
ordering and revising of his notes.

The banquet took place in October of 1517, and the mechanical lion
Leonardo had made was an immediate success. It “walked” by means of a
spring motor, into the hall, opening and closing its fierce mouth while
swaying its head from side to side. With a wand that he had been given,
Francis I stepped down from his seat and tapped the lion three times.
The toy fell apart and from it a cascade of white lilies poured out at
the king’s feet.

Also at this time there was a distinguished guest at the castle of
Amboise. He was a fellow-countryman of Leonardo and his name was
Cardinal Luigi d’Aragona. With him was his secretary Antonio de’ Beatis.
As Leonardo was now a famous member of King Francis’ court, the cardinal
paid him a visit accompanied by Antonio. The extraordinary anatomy
drawings and all his notes were shown to the cardinal; he and his
secretary were deeply impressed. They were also surprised to learn that
Leonardo had never been accorded the same recognition by his own
countrymen. Antonio de’ Beatis wrote home that “This gentleman has
written a treatise on anatomy, showing by illustrations the members,
muscles, nerves, veins, joints, intestines and whatever else is to
discuss in the bodies of men and women, in a way that has never yet been
done by anyone else. All this we have seen with our own eyes; and he
said that he had dissected more than thirty bodies, both of men and
women of all ages. He has also written of the nature of water, and of
divers machines, and of other matters which he has set down in an
endless number of volumes, all in the vulgar tongue [meaning Italian not
Latin], which, if they be published, will be profitable and delightful.”

By now Leonardo had accumulated thousands of pages of notes, and they
lay stacked in all manner of chests and boxes. Often now, as Leonardo
surveyed the work of his lifetime, he realized that he would never see
the day of their publication. Time was slipping through his fingers.
Already summer had come and gone and now the sharp winds of fall were
lifting the leaves from the ground in dancing whirls. Fortunately these
were years of peace and for the first time in a long while the people
were free of wars. The scheme to canalize the waterway to Romorantin had
grown to a vast idea for making a thoroughfare of water from the Loire
river all the way down France to Lyons and then into Italy! Leonardo,
old and ailing as he was, had surveyed parts of the rivers Loire and
Cher, braving the rough roads and crude accommodations.

In addition, Leonardo had designed a castle for Francis I’s widowed
mother in Romorantin. This castle was never built, but many of the ideas
that Leonardo had incorporated in its design were used in the gigantic
and magnificent castle of Chambord. Also, at Francis’ request, he had
reviewed the work being done at the castle in Blois and there is reason
to think that the beautiful outside stairwell that spirals from left to
right might have been designed by Leonardo.

In February of 1517, a son had been born to Queen Claude and Francis I.
The king decided to postpone the baptism of the dauphin (the title given
to the eldest son of a French King) until May of the following year. At
that time there would be a double celebration at Amboise, for a nephew
of Pope Leo X, the young Lorenzo de’ Medici, was being married to
Madelaine d’Auvergne. As usual, Leonardo was given the assignment of
preparing the festivities. Although he was fond of preparing these
entertainments, Leonardo now felt the pressure of time; for indeed, the
interruptions of this eager young king were sometimes a hardship. He
felt that his years were drawing to an end. His notes were unfinished
and his dreams of extending man’s knowledge of his world and of himself
were hindered not only by such petty chores but also by the limits of
his own physical endurance.

As Leonardo was sketching one day from the window of his room where he
could see the castle walls and the chapel of Saint-Hubert, he set aside
the drawing for a moment to write a memorandum to himself. “Write of the
quality of time as distinct from its mathematical divisions.” Was this
extraordinary man sensing the road down which Einstein—in his studies of
relativity—was to travel hundreds of years later?

Spring arrived again and with it came the first wild flowers and roses,
the songs of the birds in the woods and the blossoming of the chestnut
trees. The time for the double celebration came, too, and Leonardo was
seen busily preparing the decorations and mechanical delights for the
large crowds already assembling. In addition to the tournaments-at-arms
that so delighted the king, there was to be a mock battle with a
besieged city, and for this Leonardo had had constructed imposing castle
walls of wood with a backdrop of a city’s spires and towers. The party
lasted for weeks, and the climax was performed on the lawns of
Leonardo’s house where a great ballroom had been set up. Here he
repeated an earlier success, the one that had so enchanted Ludovico’s
guests so many years ago in the Sforza castle at Milan. There was again
a dome over the ballroom across which the stars moved mechanically and
artificial figures representing various gods and goddesses spoke and
sang by means of a hidden choir, while the sun and moon shone in their
own lights.

This display ended the festivities. It was already late June and
Leonardo was anxious to return to his plans for the water route to
Italy. There was the area near Sologne which, when flooded, would make
the surrounding countryside a marshland. This would have to be drained
by the same method as he had planned for the Piombino and the Pontine
marshes. Francis I was interested, too, in the improvements Leonardo had
suggested for his own castle, and he would have to talk with the castle
superintendent about them. As always, there seemed to be so many things
to do, to plan, to work on. Then Leonardo wrote in his notes: “On the
24th of June, the day of St. John, 1518, at Amboise, in the palace of
Cloux....” and underneath, “I will continue—”

“_I will continue_—” It was almost a note of defiance against the
obstacles of advancing age and sickness and the interruptions of the
practical world.


The sound of jingling spurs and bridle chains and the snorting of many
horses announced another surprise visit from the young king. Leonardo
could hear him below shouting something to Battista, the servant who had
come to Amboise with Leonardo. Now, as usual, Francis was running up the
stairs with all the energy of youth shouting for “le maître” (the
master). Resignedly and with patient humor, Leonardo stepped out to
greet the king. The gold chains around Francis’ thick neck and over his
broad chest glinted in the semi-light of the hall, and he was holding
his plumed hat at his side and mopping his forehead with a dainty
embroidered handkerchief.

“Master Leonardo! We are going on a tour of the river and I want you to
look at the place that I told you about. Where I want to put that
bridge. You remember?”

“Sire, give me but a moment to gather some material together.”

A chest was made ready and soon Leonardo was at the door, calling to
Francesco and Battista to help him into the saddle of his horse, while
the king’s servants hoisted the chest onto one of the carts already
piled high with tents and provisions.

When Francis was restless—which was often—a “tour” could mean many hours
or many days of travel. Wagons were always kept ready with all the
equipment for a long journey and Leonardo, himself, had learned to
accept these sudden whims and kept chests of his own ready for any such
trip. Now, as always, the king kept his horse reined back out of regard
for this tall, stooped man with the long beard and simple clothes.

Yet when Leonardo returned from this “tour” he realized that he could no
longer make such trips. The hardships of sleeping in tents, riding over
the hot roads, and the necessary work involved in surveying the possible
sites for a bridge had left him almost exhausted. He had made one
suggestion, however, and that was to build houses that could be carried
and then assembled with a few wooden locking devices, then just as
quickly taken down and moved to the next place. They could also be left
standing where the country people could use them while the court was
away. Indeed, such structures would seem to be the ancestors of our own
prefabricated houses.

The winter of 1519 was a bitter one. When the cold fog spread over the
valley shrouding the bare trees it chilled the big, white-washed rooms
of Cloux. The wind blew down from the north sending blasts down the
chimneys and scattering ashes and sparks. Leonardo, huddled against the
huge fireplace with its roof projecting into the room, pulled his black
cloak lined in soft leather around him and reminded himself to include
it in his will for Mathurine, the faithful domestic who cooked for him
and took care of his house.

The aged Leonardo, who had observed and analyzed so much of man and
nature, knew now that his own days were numbered. When the first, pale
sunlight of March shone through the small leaded-glass windows of his
house, he applied to the king for permission to make out his own will.
French law demanded that the property of any foreigner dying in France
went to the Crown. The permission was granted, and on April 23, 1519,
Guillaume Boureau, the Royal Notary of Amboise was summoned with
witnesses.

To his half-brothers in Florence Leonardo left his property at Fiesole
and four hundred ducats. To his faithful friend and companion, Francesco
de’ Melzi, nobleman of Milan, Leonardo willed his notes, drawings, and
paintings. Battista was given the income that Louis XII had granted
Leonardo from the tolls of the canal at San Cristoforo near Milan.
Mathurine was granted the “good black cloth, trimmed with leather” and
two ducats. Moreover, Leonardo outlined in detail the plans for his own
funeral, right down to the use of ten pounds of candles.

Too weak now to stand any more, Leonardo was confined to his big
four-poster bed with the canopy. From it he could see the tracery of the
Chapel of Saint-Hubert against the pale, foreign sky through the little
window in the corner. The vicar of the church of Saint-Denis was called,
with two priests and two Franciscan friars, and Leonardo received the
last sacraments at his bedside.

An entry in his notes reads, “While I thought I was learning to live, I
have been learning how to die.” But death was not easy for him. With
tears rolling down his sunken cheeks for “his wasted life,” he died on
May 2, 1519—fighting even this final interruption to all his work.

King Francis I, who was at St. Germain-en-Laye with his court, wept when
the news was brought to him. Francesco de’ Melzi was so overcome with
grief that he waited until June before writing to the half-brothers of
Leonardo of the Master’s death. He wrote, in part, “He was to me the
best of fathers, and it is impossible for me to express the grief that
his death has caused me. Until the day when my body is laid under the
ground, I shall experience perpetual sorrow, and not without reason, for
he daily showed me the most devoted and warmest affection.”

And in a closing paragraph Francesco added these words: “His loss is a
grief to everyone, for it is not in the power of nature to reproduce
another such man.”



                                   14
                      _Mankind’s Debt to Leonardo_


When Leonardo died his notebooks began their separate journeys into
obscurity. They traveled to different lands and became parts of widely
disparate collections. It has only been within the last fifty years that
efforts were made to bring them all together between the covers of one
volume—a dream that Leonardo himself entertained but never realized. As
the manuscripts and drawings were brought to light, translated and
published, the extraordinary scope of Leonardo’s scientific explorations
was revealed.

Mathematician, anatomist, botanist, astronomer and geologist form only
part of the long list of his accomplishments and give the clue to the
man who considered all the natural world within his province of study.
Because of the universality of Leonardo’s scientific thought he has been
frequently mentioned as the forerunner of such men as Galileo Galilei,
Sir Isaac Newton, James Watt, Francis Bacon and William Harvey. Although
Leonardo cannot be credited with the actual discoveries that these men
made, his methods of investigation pointed the way down the paths that
they would follow.

The key to Leonardo’s methods lies in a quotation from his notes on
vision. He wrote of vision as _saper vedere_—“to know how to see”—and he
referred to the eye as “the window of the soul.” Again and again, he
stressed the importance of observation and personal experience. Although
he himself was well read, he emphasized that “science comes by
observation not by authority.” His supreme talent for drawing underlines
his credo and is inseparable from his science. What he saw in the
natural world about him needed investigating. The results of these
investigations were transformed into drawings as the most certain method
for passing this knowledge along to others. The best example of this
attitude is represented by his anatomical studies. To merely draw the
living figure in front of him was not sufficient—it was imperative to
know what he was drawing. He turned to the dissecting room and after
intensive study produced some of the finest anatomical drawings in the
world—and among the easiest for others to understand.

What Walter Pater wrote of the Renaissance—“in many things great rather
by what it designed or aspired to than by what it actually
achieved”—could be a summation of Leonardo’s own lifetime of effort in
science. He labored to bring mankind from the morass of medieval
superstitions onto the firm ground of natural facts. With an insatiable
curiosity Leonardo attempted the impossible task of encompassing all
knowledge. Thus he established his right to immortality—for it was an
attempt that shone like a beacon in a world dark with ignorance.



                 _Significant Dates in Leonardo’s Life_


         1452  April 15. Birth of Leonardo.
         1467  Commences apprenticeship with Verrochio in Florence.
         1478  Commissioned for altarpiece in the Palace of the
               Signoria.
         1481  Commissioned to paint an altarpiece for Convent of San
               Donato.
   1482-83(?)  Leonardo leaves Florence for the court of Ludovico
               Sforza in Milan.
         1483  Begins equestrian monument of Francesco Sforza for
               Ludovico.
      1484-86  Plague in Milan.
         1490  April 23. Recommences equestrian monument and starts
               book on light and shade.
         1496  Meets with Fra Luca Pacioli, professor of mathematics.
         1498  _The Last Supper_ completed.
         1499  Apr. Land awarded to Leonardo near Porta Vercellina.
               Oct. French occupy Milan. Dec. Leonardo leaves Milan
               with Pacioli.
         1500  Leonardo arrives in Mantua. Travels to Venice and
               returns to Florence.
         1502  In the service of Cesare Borgia.
         1503  Returns to Florence, commences work on a canal to sea.
         1504  Begins the painting of battle of Anghiari. Father dies.
               Attempt at flight (?).
         1506  May. Leaves Florence for Milan at summons of Charles
               d’Amboise, French military governor.
         1507  Sept. Goes to Florence to settle father’s will.
         1508  July. Returns to Milan.
         1511  Works with Marc Antonio della Torre on anatomical
               research.
         1512  French lose Milan.
         1513  Leonardo leaves Milan for Rome. Serves Giuliano de’
               Medici, brother of Pope Leo X.
         1516  Leonardo leaves Rome for France to serve King Francis I.
         1519  May 2. Death of Leonardo.



                                _Index_


                                   A
  Abbaco, Benedetto dell’, 5
  Adda river, 124
  “Adoration of the Magi,” 29, 30
  Adriatic, the, 62, 93
  “Air conditioner,” 69
  Air, study of, 65, 66, 99
  “Alarm clock,” 57
  Albert of Saxony, 81
  Alessandria, fortress of, 83
  Alfonso of Calabria, 38
  Alps, the, 37, 67
  Amadeo, Antonio, 58
  Amadori, Albiera di Giovanni, 2
  Amadori, Alessandro, 3, 111
  Amboise, _see_ Chateau d’Amboise
  Amontons, 134
  Anatomy, human, 52, 53, 107, 109, 119, 125-127, 138
  Anchiano, 2
  Anemometer, 65, 66
  Anemoscope, 65
  Anghiari, battle of, 103, 110, 113
  Aquadello, 124
  Aquila, Battista dell’, 139
  Arabs, the, 54
  Archimedes, 41, 67, 81, 134
  Architecture, 50, 58
  Argyropoulos, John, 17
  Aristotle, 17, 23, 42, 48, 81, 89
  Arithmetic, 77
  Arithmetico, Benedetto, 16
  Armored vehicle, 39, 40
  Arno river, 25, 31, 96, 100-106, 109
  Arrezzo, 93
  Ascanio, Cardinal, 83
  Astronomy, 80-82, 104, 105
  Atlantic Ocean, 19
  “Automobile,” 32, 33
  Autopsies, 107
  Avicenna, 53


                                    B
  Bacon, Francis, 160
  Bacon, Roger, 120
  Badia, the, 7
  Battista, 155, 157
  Bayzid II, 94
  Beatis, Antonio de’, 151
  Bianca Maria, 64
  Bible, the, 62, 104, 141
  Birds, flight of, 24, 65, 66, 76, 99, 119
  Black Death, _see_ Bubonic plague
  Blois, 152
  Bologna, 144
  Bombard, 26
  Bombs, 39
  Borgia, Cesare, 82, 86-97, 102, 139
  Borgias, the, 102
  Botticelli, Sandro, 33
  Boureau, Guillaume, 156
  Bramante, 68, 131
  Bridge building, 95
  Bubonic plague, 45-47
  Buonarroti, Michelangelo, _see_ Michelangelo


                                    C
  “Camera obscura,” 55
  Campo Morto, battle of, 38
  Cannon, 26, 33, 41
  Caravaggio, siege of, 124
  Cardano, Girolamo, 113
  Carles, Geffroy, 115, 116
  Carpentry, 135, 136
  Cassano, castle of, 124
  Castel’ Sant’ Angelo, 130
  Caterina, 2
  Cellini, Benvenuto, 100
  Centrifugal pump, 121, 122
  Cesena, 94
  Chambord, castle of, 152
  Charles d’Amboise, 94, 114-117, 121, 124, 127, 139
  Chateau d’Amboise, 147-156
  Cher river, 152
  Christ, 30, 74, 77, 78
  Church of the Annunciation of the Servite Order of Monks, 90
  Church, the, 18, 48, 53, 63, 104, 145
  Cioni, Andrea di Michele di Francesco de’, _see_ Verrochio, Andrea
          del
  City Planning, 44, 45, 47
  City-states, 9, 10
  Civitavecchia, 143, 144
  Cloux, Manoir de, 148, 154, 156
  Coins, minting of, 47
  Collections, 4
  Columbus, Christopher, 19
  Constantinople, 95
  Corte, Bernardino da, 83
  Corte Vecchia, 56
  Coulomb, A. C., 17, 134
  Council of Eighty, 109
  Council of Florence, 23, 106
  Councilors and Tribunal of Venice, 89
  Credi, Lorenzo di, 13
  Cusanus, Cardinal, 42


                                    D
  Dams, 101
  Danti, Giovanni Battista, 96, 97
  d’Aragona, Cardinal Luigi, 151
  Darwin, 105
  d’Auvergne, Madelaine, 153
  David, statue of, 106
  _De Ludo Geometrico_, 134
  d’Este, Beatrice, 60, 61, 69, 86
  d’Este, Isabella, 86, 87, 91
  Diocletian, Emperor, 135
  Diseases, 109
  Dissection, 53, 126, 145
  Diver’s suit, 89
  Drawing, _see_ Painting
  Drum, mechanical, 61
  Dynamics, 140


                                    E
  Earth, the, 104, 105
  Eclipse of the sun, 48
  Einstein, 153
  Equilibrium, 141
  Euclid, 54, 91
  Eye, the, 54, 55


                                    F
  Ferdinand, King of Naples, 25, 27
  Ferrara, 70
  Ferrari, Ambrogio, 42
  Fiesole, 111, 113, 156
  Flemish painters, 15
  Flight,
      of arrow, 82, 83
      of birds, 24, 65, 66, 76, 99, 119
      problems of, 70, 71, 75, 76, 96-100, 111-113
  Florence, 7-19, 25-27, 32, 38, 53, 68, 93-96, 100-103
  Flying machine, 70, 71, 75, 76, 112
  Foix, Gaston de, 127
  Forts, 88
  Forum of the Caesars, 134
  Four elements, 48
  France, 67-69, 78, 82-84, 94, 114-120, 125, 127, 128, 139,
          142-145, 152
  Francis I, 143-145, 148-157
  Fraternity of the Immaculate Conception, 43, 44, 47
  Friction, 140, 141


                                    G
  Galen, 52, 53
  Galileo, Galilei, 134, 141, 160
  Genoa, 143
  Geocentric theory, _see_ Ptolemaic theory
  Geography, 18, 19
  Geology, 103, 104
  Geometry, 91, 134
  Georg, 131, 133, 140, 143, 145
  Geotropism, 79
  Germany, 47, 69
  Ghirlandaio, Domenico di Tommaso del, 33
  Giocondo, Francesco del, 98
  Giovanni “the Piper,” 100
  Gonzaga, Francesco, 86
  Gothic tradition, 50
  Gravity, 140, 141
  Greeks, the, 69
  Guido, 23
  Guild, 19


                                    H
  Hadrian, Emperor, 130
  Harvey, William, 126, 160
  Heavens, observation of, 80
  Heliocentric theory, 48, 81
  Heliotropism, 79
  Highmore, 53
  Hippocrates, 52
  Holy Roman Empire, 9
  Hooke, Robert, 141
  Horse, anatomy of the, 41
  Hydraulic pump, 74, 122, 123
  Hydraulics, 14
  Hydrodynamics, 141
  Hygrometer, 30, 31


                                    I
  Imola, 95, 96
  Inclination gauge, 66, 67
  India, 18
  _Introduction to Perspective, or the Function of the Eye_, 58
  Inventions, 25-27, 38-40
  Irradiation, 55
  Irrigation, 101
  Isabella of Aragon, 51
  Isonzo river, 88
  Istanbul, _see_ Constantinople


                                    J
  Johannes, 133, 143, 145
  Judas, 74, 77, 78


                                    K
  King Charles VIII, 67-69, 78, 82, 120, 148


                                    L
  Lake Como, 125
  Lamps, 59
  Lanfredini, Francesca, 2, 7
  “Last Supper,” 30, 72, 74, 77, 92, 99, 138
  League of Cambria, 124
  Leghorn, 100
  Leibig, 41
  Leonardo da Vinci,
      and the Church, 18, 48, 104, 145
      birth of, 2
      death of, 157
      early years of, 1-8
      illness of, 142, 150
      moves to Florence, 10
      notebooks of, 25, 29, 140, 152, 159, 160
  Levite, 118
  _Light and Shade_, 54
  Lighting, 59
  Lilienthal, Otto, 100
  Livoli river, 139
  Loches, 92
  Loire river, 147, 149, 152
  Lombardy, 37, 62, 78, 82, 83, 121,148
  Louis XII (of Orleans), 78, 82, 92, 94, 114, 116, 119, 124, 142,
          157
  Louvre, the, 44
  Lucullus, 130
  Lyons, 152
  Lyre, silver, 34, 35


                                    M
  Machiavelli, Niccolò, 96, 100, 102, 106, 109
  Machine gun, 27
  Machinery, improvement of, 16
  Madonna Lisa, _see_ Mona Lisa
  Malaria, 139
  Mandeville, Sir John, 103
  Manenti, 88
  Mantua, 84, 86, 87
  Mapmaking, 19, 93, 95, 96, 100, 101
  Martelli, Piero, 118
  Martini, Francesco di Giorgio, 58
  Martino river, 139
  Mathurine, 156, 157
  Maximilian I, 64
  Medici, Giovanni de’, 130
  Medici, Giuliano de’, 21, 130, 132, 138-146
  Medici, Lorenzo de’, 16, 21, 26, 27, 29, 35, 39, 127, 130, 132,
          146, 153
  Medici, Piero de’, 10, 16
  Medicis, the, 10, 21, 23, 26, 27, 33, 34, 68, 130, 131, 140, 142,
          146
  Melzi, Francesco de’, 117, 128, 130, 140, 142, 145, 150, 155, 157,
          158
  Michelangelo, 106, 107, 113, 131, 137, 144, 145
  Middle Ages, 81, 104
  Migliorotti, Atalante, 35-38, 87
  Milan, 9, 33-48, 60, 64, 68, 78, 82, 83, 85, 95, 114-128, 143, 144
  Milan cathedral, 50
  Military,
      defenses, 88, 89
      machines, 25-27, 33, 38-40
  Millstones, 75
  Mitre valve, 123
  Mirrors, 133
  “Mona Lisa,” 99, 103
  Monferrato, 62
  Monte Albano, 1, 2, 5
  Monte Cecero, 113
  Montorfano, 72
  Muscles, 109, 119
  Music, 34, 35


                                    N
  Naples, 9, 27, 68, 69
  Needle sharpener, 75
  Netherlands, the, 95
  Newton, Isaac, 24, 56, 123, 141, 160
  Newton’s First Law of Motion, 123
  Newton’s law of gravitation, 83
  _Notes_, 14
  Novara, battle of, 92


                                    O
  Odometer, 69
  Oggionno, Marco d’, 58
  Orient, the, 89
  Ornithopter, 111, 112


                                    P
  Pacioli, Fra Luca, 76, 77, 80, 84, 86-91, 133
  Padua, 125
  Painting, 4-7, 29-32, 43, 44, 71, 72, 91, 99, 105, 110, 112
  Palatine hill, 135
  Palazzo della Signoria, 12, 21-25, 103
  Palazzo Vecchio, 12
  Parachute, 71
  Paris, 44
  Parma, 138
  Pater, Walter, 161
  Pavia, 51, 58, 125
  Pazzi conspiracy, 21, 23, 25
  Pazzi, Francesco de’, 23
  Pera, 95
  “Periscope,” the, 89
  Perugia, 96
  Perugino, Pietro, 13, 33, 107
  Pesaro, 93
  Peschiera, 124
  Pharisee, 118
  Philiberta, 142
  Phyllotaxis, 79
  Physics, 17
  Piazzetta, the, 87
  Pincio hill, 130
  Piombino, 93, 139, 154
  Pisa, 25, 100-102, 110
  Pitti Palace, 31
  Plague, _see_ Bubonic plague
  Plants, study of, 79, 80
  Platonic school, 54
  Pliny, 23
  Plutarch, 81
  Pollaiuolo, 53
  Ponte Vecchio, 31
  Pontine marshes, 139, 154
  Pope Alexander VI, 82, 92, 102
  Pope Innocent VIII, 63
  Pope Julius II, 124, 127, 128, 130, 131
  Pope Leo X, 130-132, 139, 142-146, 153
  Pope Sixtus IV, 21, 33
  Porta del Popolo, 129
  Porta Romana, 29
  Porta Vercellina, 79, 115
  Porto Cesanatico, 94
  Portugal, 26
  Predis, Bernardino de, 47
  Predis, Giovanni Ambrogio de, 43, 44, 47, 56
  Ptolemaic theory, 48
  Ptolemy, 23, 54, 103


                                    Q
  Queen Claude, 152


                                    R
  Raphael, 107, 131, 137
  Ravenna, battle of, 127
  Red Book of the Painters of Florence, 19
  Reflection, law of, 56
  Renaissance, 89, 104, 125, 161
  Riario, Girolamo, 21, 38
  Rimini, 93
  Rome, 9, 33, 47, 69, 128-146
  Romorantin, 150, 152
  Rosate, Ambrogio da, 63
  Rumford, 56
  Rustici, Giovanni, 118


                                    S
  “St. Anne with the Virgin and Child,” 91, 92
  St. Augustine, 42
  Saint-Denis church, 157
  St. Germain-en-Laye, 157
  Saint-Hubert, chapel of, 153, 157
  St. John, 118, 154
  St. John the Baptist, 151
  St. Luke, 19
  St. Mary of the Virgin, 96
  St. Peter’s, church of, 131
  Salai, 86, 115
  Salviati, Francesco, 21
  San Bernardo, chapel of, 23
  San Cristoforo, 157
  San Donato a Scopeto, 29
  San Lorenzo, 144, 145
  San Marco, Little Square of, 87
  Sanseverino, Galeazzo da, 82, 83
  Sant’ Onofrio, hospital, 107
  Santa Croce, church of, 107
  Santa Maria delle Grazie, 71, 78
  Santa Maria Novella, 107
  Sanzio, Raffaello, _see_ Raphael
  Savoy, 142
  Scarlione, Bartolommeo degli, 43
  Sculpture, 41, 49, 52-54, 58-64, 118
  Sforza, Duke Gian Galeazzo, 51, 56, 68, 120
  Sforza, Francesco, 41, 47, 49, 61, 64
  Sforza, Francesco (child), 68
  Sforza, Ludovico, 33-47, 51, 52, 56, 57, 60-72, 76-79, 82-84, 92,
          115, 117, 120, 138, 146, 154
  Sforza monument, 49-59, 61, 64, 120
  Sforzas, the, 40, 56, 57, 71, 79, 83, 117, 120, 154
  Shells, 62, 63
  Signoria, the, 96, 100-106, 110, 114, 116
  Sistine Chapel, 33, 132, 137
  Soderini, Piero, 103, 106, 109, 114-116
  Sologne, 154
  Spain, 18, 69, 127, 139, 142, 143
  Statics, 140
  Steam, 41
  Strabo, 23, 103, 104
  Swiss, 127, 128, 143


                                    T
  Ticino gate, 44
  Torre, Marcantonio della, 125, 128
  Toscanelli, Paolo del Pozzo, 18, 19, 42, 93
  Touraine, 92
  Trivulzio, Marshal Gian Giacomo, 120, 121, 125, 128, 143
  Turks, the, 87-90, 94
  Tuscany, 93
  Tyrrhenian coast, 143


                                    U
  Uffizi Gallery, 25, 32
  University of Padua, 125
  University of Pavia, 63
  Urbino, 93


                                    V
  Valentinois, Duke of, _see_ Borgia, Cesare
  Valois, Marguerite de, 150
  Vatican, the, 47, 130-145
  Venice, 9, 69, 87-89, 124, 125, 127
  Verrochio, Andrea del, 7, 12-19, 23, 118
  Via Ghibellina, 90
  Vigevano, 68, 75
  Vinci, 2, 13
  Vinci, da, Giuliano, 117
  Vinci, da, Piero, 2-7, 10, 12, 90, 106, 117
  “Virgin of the Rocks,” 44
  Vitellozzo, 93
  Vitruvius, 77


                                    W
  Water, study of, 67, 101, 102, 121, 122
  Watt, James, 160
  Witelo, 58


                                    Y
  Yugoslavia, 88

    [Illustration: Endpaper, portraits of scientists]

    [Illustration: Endpaper, names of scientists]



                              Transcriber’s Notes


—Silently corrected a few typos.

—Retained publication information from the printed edition: this eBook
  is public-domain in the country of publication.

—In the text versions only, text in italics is delimited by
  _underscores_.





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