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Title: The Borghesi Astronomical Clock in the Museum of History and Technology - Contributions from the Museum of History and Technology, Paper 35, the Smithsonian Institution United States National Museum Bulletin 240
Author: Bedini, Silvio A.
Language: English
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Transcriber's note:

      This is Contributions from the Museum of History and
      Technology, Paper 35, from the Smithsonian Institution
      United States National Museum Bulletin 240, comprising
      Papers 34-44, which will also be available as a complete

      The front material, introduction and relevant index entries
      from the Bulletin are included in each single-paper e-book.

      Corrections are listed at the end of the e-book.

      Characters within curly braces following a carat character
      are superscripted (example: Bart^{o}),

Smithsonian Institution
United States National Museum
Bulletin 240


Smithsonian Press

Museum of History and Technology

Contributions from the Museum of History and Technology

Papers 34-44 on Science and Technology

Smithsonian Institution . Washington, D.C. 1966

       *       *       *       *       *

_Publications of the United States National Museum_

The scholarly and scientific publications of the United States National
Museum include two series, _Proceedings of the United States National
Museum_ and _United States National Museum Bulletin_.

In these series, the Museum publishes original articles and
monographs dealing with the collections and work of its constituent
museums--The Museum of Natural History and the Museum of History and
Technology--setting forth newly acquired facts in the fields of
anthropology, biology, history, geology, and technology. Copies of each
publication are distributed to libraries, to cultural and scientific
organizations, and to specialists and others interested in the different

The _Proceedings_, begun in 1878, are intended for the publication, in
separate form, of shorter papers from the Museum of Natural History.
These are gathered in volumes, octavo in size, with the publication date
of each paper recorded in the table of contents of the volume.

In the _Bulletin_ series, the first of which was issued in 1875, appear
longer, separate publications consisting of monographs (occasionally in
several parts) and volumes in which are collected works on related
subjects. _Bulletins_ are either octavo or quarto in size, depending on
the needs of the presentation. Since 1902 papers relating to the
botanical collections of the Museum of Natural History have been
published in the _Bulletin_ series under the heading _Contributions from
the United States National Herbarium_, and since 1959, in _Bulletins_
titled "Contributions from the Museum of History and Technology," have
been gathered shorter papers relating to the collections and research of
that Museum.

The present collection of Contributions, Papers 34-44, comprises
Bulletin 240. Each of these papers has been previously published in
separate form. The year of publication is shown on the last page of each

    _Director, United States National Museum_

       *       *       *       *       *

Contributions from the Museum of History and Technology:
Paper 35





    DESIGNER BORGHESI                              33

    CLOCKMAKER BERTOLLA                            34

    FIRST BORGHESI CLOCK                           38

    SECOND BORGHESI CLOCK                          41


    LAST YEARS                                     57


    APPENDIX                                       71

    BIBLIOGRAPHY                                   76

[Illustration: Figure 1.--THE DIAL PLATE of the Borghesi clock, showing
the horary and astronomical indications which are automatically

_Silvio A. Bedini_

_The Borghesi Astronomical Clock_

_In the Museum of History and Technology_

     _The history of the 18th-century Borghesi astronomical clock is
     described here from contemporary source material. The evolution
     of its design by Father Francesco Borghesi and the building of
     the complex mechanism devised by the clockmaker, Bartolomeo
     Antonio Bertolla, is a story of the vision of one man turned
     into reality by another. The result of their collaboration is
     the unique, astronomical timepiece now in the Museum of History
     and Technology._

     THE AUTHOR: _Silvio A. Bedini is curator of mechanical and
     civil engineering in the Smithsonian Institution's Museum of
     History and Technology._

     "... All this work I had performed eagerly, so that, while in
     my room, I might contemplate leisurely, both during the day and
     in the night, the true face of the heavens and of the seas
     unobscured by clouds, even though I had no astronomical

With these words, Father Francesco Borghesi (1723-1802) of Mechel
described the reasons which inspired him to invent a unique astronomical
clock which is now in the horological collection of the Museum of
History and Technology.

This complicated mechanism, which performs a multitude of functions, was
designed by Father Francesco Borghesi, a secular priest in Venezia
Tridentina. It was constructed in 1764 under his direction by a
provincial clockmaker named Bartolomeo Antonio Bertolla (1702-1789) of
Mocenigo di Rumo. It was the second of two complicated astronomical
clocks which Father Borghesi designed and which Bertolla constructed.
According to contemporary sources, this clock was presented to the
Empress Maria Theresa of Austria soon after its completion.

Its history is rather hazy, except for the fact that in 1780 this second
Borghesi timepiece was still in the Imperial Palace in Vienna. The clock
was again noted in 1927 when it was sold at a public auction in New
York.[2] Subsequently, it was acquired for the Smithsonian Institution.

Development of Astronomical Clocks

The history of the great theoretical and mechanical achievement which
the Borghesi clock represents has been most adequately covered
elsewhere.[3] Consideration of the development of equation and
astronomical clocks is required here only for the purpose of relating
the Borghesi timepiece with the other significant developments in this
branch of horology.

The invention of the anchor escapement in about 1670, and the consequent
greater accuracy in time-telling, led to increased preoccupation with
precision. Daily differences in time as recorded by sundials and clocks
became more noticeable. Finally, in the second half of the 17th century,
some attempt was made to construct mechanical clocks combined with
sundials as well as astronomical clocks.

With the improvement of precision time-telling, it became necessary to
reconcile the actual difference between true and mean time. Although a
great variety of time-equation tables were produced, there was a
considerable margin for error in their use. This led to the construction
of mechanical clocks in which the equation of time was automatically
accomplished. A few were produced late in the 17th and early 18th
century at considerable cost and, consequently, with little popularity.
Equation sundials were also developed which were elaborately ingenious,
but they were not completely practical. Inevitably, they were supplanted
by the mechanical equation clock.

Probably the first documented mention of an equation clock is in the
diary of John Evelyn who recorded that in 1666 he visited the Royal
Society where he witnessed a curious clock, which showed the equation of
time, being presented by a certain Mercator. More data on the subject
appeared in the first two decades of the 18th century, when Henry Sully,
Joseph Williamson, Daniel Quare, and Thomas Tompion--who were among the
foremost English clockmakers of all time--produced elaborate examples of
these timepieces. Another significant maker was Dowe Williamson, who
became Court Clockmaker to Emperor Charles VI of Austria. In London,
Joseph Williamson produced some of the finest astronomical timepieces of
this type that have been known. The interest in the subject next shifted
to France where many fine examples were produced during the first half
of the 18th century.

Just after the middle of the 18th century, the subject of astronomical
clocks suddenly became a major horological preoccupation in another
region, namely, Austria, where the work in this field was apparently
done exclusively by members of the clergy. The earliest was Father
Philipp Matthäus Hahn (1739-1790) of Württemberg.[4] Father Hahn
considered the equation of time as only one part of a plan to represent
astronomical occurrences by means of clockwork. In addition to
planetaria and similar mechanisms, Father Hahn produced two
extraordinary astronomical, tall-case clocks, both of which survive in
public museums.

       *       *       *       *       *


The author wishes to acknowledge the valuable assistance received from
the following: DR. AMOS AVERY, Amherst, Massachusetts; MR. EDWIN A.
BATTISON, curator of light machinery and horology, U.S. National Museum;
DOTT. RICHARD BLAAS, Oesterreiches Staatsarchiv, Vienna; DOTT. ADOLFO
CETTO, librarian, Biblioteca Comunale di Trento, who made copies of
Borghesi's two volumes available; SIGNOR MARIO DI MARIO, editor of _La
Clessidra_, Rome, who permitted several of the illustrations in Sig.
Luigi Pippa's article to be used herein; MR. WALTER A. GILBERT, Norwich,
Connecticut; DR. HEINRICH LINARDI, Uhrenmuseum der Stadt Wien, Vienna;
Museo Nazionale della Scienza e della Tecnica, Milan, for their
cooperation on the descriptions and illustrations of the restored
clockshop of Bartolomeo Antonio Bertolla; and DR. EDWARD WATERS,
Division of Music, Library of Congress, Washington, D.C.

The translation from Francesco Borghesi's Latin texts, which made this
study possible, were made by: REV. NEIL HERLIHY, S.J., REV. FRANCIS J.
HEYDEN, S.J., and REV. STEPHEN X. WINTERS, S.J., Georgetown University,
Washington, D.C.; and REV. DANIEL HUNTER, O.P., and REV. ROBERT STENGER,
O.P., Dominican House of Studies, Washington, D.C.

       *       *       *       *       *

inventor and designer of the astronomical clock in the Museum of History
and Technology.]

Another of the clerical clockmakers was Father Aurelianus à San Daniele
(1728-1782), an Augustine monk in the monastery of the Imperial Court at
Vienna.[5] His four complicated astronomical clocks, which exist in
museums at present, are comparable to those produced by Father Hahn. The
third cleric was Brother David à San Cajetano (1736-1796) in the same
Augustine order to which Father Aurelianus belonged. He achieved note as
the author of various publications, including _Neue Rädergebäude_[6]
[New Construction of Wheels] relating to planet-wheels, or gear-trains
containing epicyclic elements. He constructed a clock based on an
elaborate astronomical design which was substantially different from the
others. The fourth of the ecclesiasts who designed astronomical clocks
in this period was Father Klein of Prague, who produced a complicated
astronomical timepiece in about 1738.

The fact that such important and outstanding examples of astronomical
clocks were produced exclusively by ecclesiasts in Austria during the
second half of the 18th century is especially significant. It is
particularly so when a fifth cleric is added to the group, also an
Austrian subject although Italian by heritage, in the person of Father
Francesco Borghesi.

Although only Father Borghesi's second astronomical clock is now known,
it is apparent that this example in the Museum of History and Technology
represents an experiment in astronomical time-telling comparable to any
of the timepieces produced by Father Hahn, Father Aurelianus, Brother
David à San Cajetano or Father Klein.

This combination of five clerical clockmakers who lived in the same
region during the same period of time is sufficiently unusual. However,
the fact that each of them apparently worked without association with
any of the others leads to the conjecture that a common factor must have
led them to their individual preoccupation with astronomical horology.
What the link may have been is not apparent from the surviving records
of the lives and works of these clerics. Certainly it was not an
interest in astronomy or clockmaking per se, because other than the
astronomical clocks, none of these horological inventors--with the
possible exception of Father Hahn--worked in any other aspect of the
fields of astronomy or horology. However, after a comprehensive study of
Father Borghesi's writings, there is little doubt of the religious basis
of his own inspiration.

Designer Borghesi

Father Borghesi's story takes place in the picturesque mountainous
region of what was then known as Venezia Tridentina (since 1947,
Trentino-Alto Adige) in northern Italy, along the Tyrolean border of
Austria. Because of its strategic position as the passage between
Innsbruck and Verona, the possession of the Tridentina was contested
again and again in the European wars, but during Father Borghesi's
lifetime, the Tridentina was under Austrian domination.

[Illustration: Figure 3.--PANORAMA of the village of Mechel in the
valley of the Non, birthplace of Father Borghesi.]

Deep within this mountainous district is the romantic valley of the Non,
or Anáuni, with its great forests and ancient castles. Most maps do not
mark it, and the tourist guides ignore it.[7] One of the chief
communities is Cles, with its historic Renaissance buildings. The major
city of the region is Trent on the Adige River, with its surviving Roman
relics and Romanesque and Renaissance architecture.

The little villages scattered throughout the valley of the Non played no
part in history, but such names as Mechel and Mocenigo di Rumo reflect
the interchange of sovereignty. It was in the little village of Mechel
that Francesco Borghesi was born in 1723.[8] Local records are meager
and inadequate, and many of the details of Borghesi's life must be
assumed. Inasmuch as the village was in a rural, agricultural district,
Borghesi may have come from a family of farmers, vintners, or village
tradesmen. Borghesi sought an education by entering the priesthood and
was ordained a secular priest in Salzburg. He was first assigned as
curate to the village parish of Rumo in the valley of the Non, a short
distance from his birthplace.[9] Later, he was transferred to his native
Mechel. He was inherently a man of simple tastes and of great piety. He
tended to the needs of his mountain villagers and attended the births,
weddings and deaths of his parishioners. It was during his assignment in
this tiny community that Father Borghesi met and became friendly with
the clockmaker, Bartolomeo Antonio Bertolla of nearby Mocenigo di Rumo.

Clockmaker Bertolla

Bartolomeo Antonio Bertolla was born in Mocenigo di Rumo, a short
distance from Mechel, in 1702.[10] Nothing is known of his boyhood,
other than the fact that he was mechanically inclined. At the age of 17
he was apprenticed to become a clockmaker with the master, Johann Georg
Butzjäger of Neulengbach, a small village on the edge of the great
Vienna woods.[11] This region was then part of the domain of the
Archduke of Austria, of which Sankt Pölten was the capital.

clockmaker, of Mocenigo di Rumo. The canvas in oils is owned by
descendants. In the upper left-hand corner is an inscription, now hardly
legible, indicating that the portrait may have been painted after
Bertolla's death on January 15, 1789. Translated, it states: "Bartolomeo
Antonio Bertola [sic] Celebrated Mechanician and Inventor of various
Instruments. Repairer of the clocks of Venice, Verona, Trent, and other
localities. Maker of the Work which combines the Copernican and
Ptolemaic Systems devised by Father Francesco Borghesi of Mechel,
Laureate Mathematician, and humbly offered to Her Imperial Majesty Maria
Theresa. Died in piety in his home at Rumo on 15 January 1789 at the age
of 86." (_Courtesy of Sig. Luigi Pippa of Milan._)]

[Illustration: Figure 5.--THE VILLAGE OF MOCENIGO DI RUMO in the valley
of the Non. Arrow points to Bertolla's home and workshop at far left.]

[Illustration: Figure 6.--CERTIFICATE OF APPRENTICESHIP awarded to
Bartolomeo Antonio Bertolla upon completion of his 3-year apprenticeship
at Neulengbach, dated December 27, 1722.]

Bertolla began his apprenticeship with Butzjäger under the auspices of
the Corporation of Blacksmiths of Sankt Pölten in 1719. His training was
supervised by two master locksmiths, Johann Christian Winz and Peter
Wisshofer, who were members of the Corporation, and were assigned to
serve as patrons for the apprentice. It was their obligation to make
certain that he received good care and adequate instruction from his
master. While he worked in Butzjäger's shop, Bertolla lived with the
master's family in their home.

Bertolla's 3 years at Neulengbach passed quickly as he sought to absorb
all that his master could teach him. Butzjäger was considered to be a
good craftsman in the region, yet today there is not even a mention of
his name in the lists of clockmakers. He specialized in the production
and repair of "great clocks" which included tall-case, domestic
timepieces, and tower clocks. Butzjäger treated his apprentice well, and
in return Bertolla rewarded him by being diligent and honest. His
subsequent work is sufficient indication that he developed into an
extremely skilled craftsman, and he became the equal of any clockmaker
of his time.

The 3 years of apprenticeship were completed and on December 27, 1722,
Bertolla received a certificate from the Corporation of Blacksmiths
which assured whomever it might concern of Bertolla's skill, diligence
and honesty, and permitted him to open his own shop as a clockmaker
under the auspices of the Corporation. This document, which has been
preserved by Bertolla's descendants, is an interesting record of the
organization of the trade guilds in the 18th century, and, for that
reason, has been translated from the original German:

     We, the Superiors and other masters of the honorable
     corporation of municipal blacksmiths, armorers, and of smiths,
     in the Imperial City of St. Pölten in Austria by the river
     Enns, DECLARE BY THESE PRESENTS put in force by this document
     to anyone who waits to hear.... That the honorable and able
     BARTOLOMEO ANTONIO BERTOLLA of Rumo in Lentzberg, the Tyrol, on
     the 27th day of the month of December of the year 1719 was
     consigned as apprentice for three years, in the presence of two
     sponsoring masters for the purpose, the honorable Johann
     Christian Winz and Peter Wisshofer, both of them master
     locksmiths representing the entire honorable Corporation and
     others of open shop--to the honorable JOHANN GEORG BUTZJÄGER,
     incorporated with us, citizen and master clockmaker for large
     clocks in the merchant-village of Neulengbach in Wienerwald, as
     his master of the art, would have therefore perfectly and
     rightfully worked and learned, and

     that afterwards, on the day and year noted at the bottom, he
     will be newly declared free and independent before us,
     representative of an entire and honorable Corporation and with
     open shop, of his above-mentioned master and of the two
     sponsoring masters mentioned,

     and since he eagerly requested a truthful certificate of
     apprenticeship for his honest service as an apprentice and for
     his good behavior, and we having great pleasure as well as the
     duty of favoring the truth and well knowing that the aforesaid
     BARTOLOMEO ANTONIO BERTOLLA has learned honestly the art of
     clockmaking for great clocks from his aforesaid master, and
     that he has always behaved with honesty, obedience,
     faithfulness and diligence both towards his master and towards
     us to our complete satisfaction and, therefore, we cannot in
     any manner refuse his request, rather we wish to grant it with
     a clear conscience.

     WE THEREFORE ADDRESS TO EVERYONE and to anyone in whatever
     state and rank, but particularly to those interested in our
     branch of this art, our respectful and courteous entreaty and
     request to consider BARTOLOMEO ANTONIO BERTOLLA well
     recommended for his honest apprenticeship and his good
     behavior, and to desire to favor him in every way, in such a
     manner that will assure our gratitude whenever an occasion
     presents itself.

     For this purpose, we issue, as we have declared we wish to
     issue to you, BARTOLOMEO ANTONIO BERTOLLA, this certificate of
     apprenticeship, attaching to it the seal of our Corporation.

     Executed in the city of St. Pölten on 27 December 1722.[12]

His apprenticeship over, Bertolla returned to his native region where he
soon established a reputation for himself as one of the most skillful
clockmakers in the Tridentina and produced timepieces of fine quality in
some quantity. No records have survived concerning his personal life,
but it is believed that he married probably soon after his return. He
had no children of his own. To expand his business, he eventually took
into his shop two nephews, the sons of a brother and a sister, as

Bertolla's work brought him a sufficient number of clients, and he
produced elaborate clocks for his more wealthy patrons.

In 1752, it is recorded that he repaired the great clock in the
campanile of the Church of the Assumption of the Virgin Mary in Cles,
the regional capital of the valley of the Non. The clock dated probably
from the 16th century, and it seems likely that Bertolla replaced the
original two-wheel train with a three-wheel movement, and that he added
the present anchor escapement.[13]

It is not possible to determine when Father Borghesi first made
Bertolla's acquaintance, but it may be assumed that they had become
friends in the late 1750's.

After he had come to know Bertolla, Father Borghesi apparently spent
many hours in the clockmaker's shop. He was fascinated by mechanics in
any form, and the complications of clockwork particularly intrigued him.
Bertolla was patient with the young priest, explaining the tools he had
and their uses, the clocks he produced or repaired, and the principles
which were involved. Father Borghesi listened willingly and as his
understanding of timepieces grew, his curiosity increased.

In spite of himself, the priest could not be satisfied with the ordinary
aspects of his friend's work and wanted to learn more. From a casual
pastime, the study of time became an obsession with him. There was but
one recourse: he went back to studying once again. This time it was not
theology, however, but the sciences. Every moment he could spare went
into the perusal of books on mathematics, astronomy, and associated
subjects. He progressed rapidly, driven by his overpowering interest and
aided by his quick intellect.

Little by little, Borghesi managed to acquire the basic texts that
explained this new world to him, probably borrowing them from old
seminary friends. As each new book came into his hands, he devoured it
in his desire to master its contents. He discussed each new principle or
precept that he learned with Bertolla. Together, they attempted to apply
his new learning to the calculations necessary for a timepiece which
would demonstrate the astronomical theories in visual form. Borghesi
taught himself slowly, step by step, and the result was a profound
understanding of astronomical science. He conceived the project of
constructing a great astronomical clock which he felt could be
accomplished by combining Bertolla's mechanical skills with his own
recent mastery of astronomy and mathematics.

First Borghesi Clock

It is not difficult to visualize the two men, the priest and the
clockmaker, as they sat together night after night working out their
plans. Father Borghesi would painstakingly outline the astronomical
principles he wished to have the clock exhibit and the mathematical
principles which would be involved to operate them. Bertolla
concentrated on them and tried to transcribe the principles into
functional mechanical terms, visualizing each operation in terms of
wheels and gears. Little by little the two men coordinated the numerous
elements and welded them into an operating entity. They adjourned either
to the stark simplicity of the rectory or, probably more often, to
Bertolla's little home workshop, the priest standing over his friend
while the latter worked at his bench in the dark paneled interior
illuminated only by the several lamps on the work benches.

This first clock which the two men combined to create is a monument to
the great scientific knowledge of the self-taught priest and the
technical ability of the clockmaker--a unity combining astronomical
science, mechanics, and artistry. The story of the project is told in a
little book, _Novissima Ac Perpetua Astronomica..._, which Borghesi
later published. Explaining the incentive which inspired him, and the
premises from which he began his work, he wrote:

     From the foundation of astronomical science long ago,
     innumerable [and] repeated observations of both ancient and
     modern astronomers, emerged at last from their hiding places.
     Made light of by the jests of so many outstanding intellects,
     they have so successfully brought to light the paths of the
     stars and their motions, which are more complicated to us than
     the Gordian knots. Now it is possible for even an amateur in
     astronomy, sufficiently instructed, to predict for any given
     time not only the mean position of the planets, but also their
     true longitude and latitude, and even the true time of their
     conjunctions, and their ecliptic oppositions, with all the
     attendant circumstances. Yet, until now, no hypothesis has been
     devised which would force an automaton to show to us, before
     our very eyes, the eclipses of the planets in their true and
     certain times.

     For though there have been men seeking with all their might to
     bind by laws their artificial heavens, by I know not how many
     and how great calculations, and to systematize the complexities
     of the rotations of celestial bodies; nevertheless, all of
     them, as if by common agreement, considered themselves to have
     made great contributions to mechanico-theoretical astronomy.
     However, they have only attained, even though closely, the mean
     locations of the secondary mobiles, and those by a certain
     rather crude calculation. Some attained by more, some by less,
     but all by some degree of wandering from the truth, either worn
     out by the intricacies of the motions, or deceived and
     deceiving by the errors of their calculations. This fact those
     well know, who, setting about to collect information of this
     kind, even those publicized not long ago, with true
     astronomical calculation, have been bored to death while
     digging out by the most elementary and superficial arithmetical
     torture, the worst of fallacies spontaneously erupting from

     It would seem that true calculations alone can be desired in
     mechanico-astronomics. Long study had not only convinced me
     that an automaton was within the realm of possibility, but that
     there were many mechanical systems by which it could be
     achieved. I girded myself for a new project and developed it
     theoretically from the ground up, but under such unhappy
     auspices that not only did all hope fail that anyone would ever
     appear who might have seemed willing to set his hand to the
     work, but that the new discovery itself was scoffed at by many
     as altogether a nightmarish delirium of an unbridled

The first months of the project must have seemed like an inspired dream
to the two men, and then must have followed a period of hopeless
depression. Bertolla undoubtedly felt many times that the clock was an
aspiration far beyond their combined abilities and means, but the priest
would not be thwarted in his ambition and refused to abandon the
project. He felt that it was a work that they were destined to produce.
Many times, he wrote, he chided and begged and shamed his erstwhile
partner into resuming the project where it had been last abandoned.
Little by little, the first clock began to take form. As each new
difficulty was encountered, the two men would go back over the notes and
sketches to trace the problem to its source. Often a new part of the
mechanism would nullify another which had thus far operated
successfully, and a complete rearrangement would be required.

[Illustration: Figure 7.--TITLE PAGE of Father Borghesi's first book.
The translation in its entirety is: "The Most Recent, Perpetual,
Astronomical Calendar Clock: Theoretical--Practical: by means of which
besides the hours, the minutes and seconds; the current year, the month;
the day of the month and the day of the week; the dominical letter,
epact, and thence, the day of all the feastdays, both fixed and movable;
the solar cycle; the golden number; the Roman indiction; the dominant
planet of any year and its sign; the phases of the moon and its mean
age: and all the motions of the sun and the moon as to longitude,
latitude, eccentricity, etc., are immediately seen, so accurately that
[not only] the true new full moons and the true quadrature, etc., of the
sun and moon appear, but also, all solar and lunar eclipses--both
visible and invisible; as in heaven, so on the clock, they are
conspicuously celebrated in their true times, and those of the past and
those of the future, with their circumstances of time and duration,
magnitude, etc., can be quickly determined. All this was devised and
brought to light by the author, Francesco Borghesi of Anáuni, a secular
priest of Trent, A.A.L.L. & Doctor of Philosophy. (Trent: From the
printshop of Giovanni Battista Monauni, With Permission of Superiors.)"
(_Title page reproduced by permission of the Biblioteca della Citta di

Again and again, Bertolla threw up his hands in despair and begged
Father Borghesi to abandon the enterprise. He protested that he was not
capable of producing such a complicated mechanism; he had neither the
tools nor the skill. The priest wished to produce a clock such as the
world had never seen before, such as the greatest scientists and
clockmakers of all time had never been able to make. But Bertolla felt
that he was only a provincial craftsman who could not hope to surpass
them all with only his simple tools and training.

In his book on the first clock, _Novissima Ac Perpetua Astronomica..._,
Father Borghesi wrote that when he had finally come within a few weeks
of the embryo stage in the development of his clock, he was faced with
the problem of bolstering the sagging enthusiasm of Bertolla. The
clockmaker's original enthusiasm had shown promise of great results, but
as the days passed and the problems of the multiplex and generally
unfamiliar apparatus to be forged for the workings of the automaton
became more complex, his ardor decreased. Finally, Bertolla became so
discouraged by the scoffers and frustrated by the fact that the work was
insufficiently organized that Father Borghesi wrote that "it almost
became a harder task for me to bolster up by daily opportunity and
importunity the failing patience of the artisan, frightened away from
the work already begun, than it was for me to extract from the inner
recesses of mathematics and astronomy, without light and without a
guide, the whole fabric of the machine itself!"

In spite of Bertolla's protests, Father Borghesi prevailed, reviving his
friend's interest once more until the two were deep in the project
again. Months passed as they worked together on the mechanism and it
seemed as if they lived for no other purpose. Inevitably, Bertolla's
health began to suffer, undermined as it was by the constant nervous
tension, and he eventually became ill from mental strain. He was forced
to spend some time in bed, and for many weeks the subject of the clock
was not discussed. Bertolla's other work, by which he made his living,
suffered and it was several months before he was able to return to his
little shop.

One year passed into another and the work progressed slowly. The first
clock, which easily should have been finished in less than a year, was
not completed until after three full years had passed. However, when the
priest and the clockmaker put the finishing touches to their great
clock, the result surpassed the greatest possible expectations, for it
was truly a masterpiece. Not only did it illustrate the ecliptic
phenomena of the moon, the sun and earth occurring in their proper time,
as well as many other things, but it showed these operations as they
succeeded in proper order, taking place through the centuries.

With mutual feelings of great pride, the two friends surveyed the result
of their three years of endeavor. Bertolla realized that he had reached
a point of maximum achievement in his work. He probably felt that now he
could relax again, that his sleep would no longer be troubled by
confused nightmares of wheels and gears that did not mesh together. Time
was to prove otherwise.


Father Borghesi soon came to the conclusion that it would be desirable
to have a written description to explain the mechanism of the clock and
its many indicators. He thereupon wrote out the story of how the clock
was made, the reasons for embarking on the enterprise, the difficulties
he had encountered, and the success which had crowned his and Bertolla's
mutual labors. Finally, he described the operation of the clock's
mechanism and the functions of its array of indicators.

The little book was written in Latin and only a few copies were printed,
presumably at the priest's own expense, on a handpress by Giovanni
Battista Monauni, printer to the Bishop in Trent. The little volume was
stated by contemporary writers to have been published in 1763, although
no date appears on the title page. The title translated is, in part,
_The Most Recent, Perpetual Astronomical Calendar Clock,
Theoretical--Practical...._ The work begins with an introduction for the
reader in which Father Borghesi stated that:

     ... the little work, which, as far as I was concerned could
     easily have been finished in a year, was only completed after
     about three years. Fortunately, however, it was so far beyond
     the expectations of most, that not only am I able to foretell
     with certainty all the lunar ecliptic phenomena and the solar,
     or rather terrestrial, phenomena, carefully worked out in their
     true periods, among many other matters exhibited by the
     machine; but also, within a few hours, I can exhibit by
     altogether tangible evidence to the skeptics and the doubting
     those very same phenomena, occurring within the space of many
     years, or even centuries, and succeeding one another in proper
     order, with their many attendant circumstances. I was not much
     concerned about the other eclipses, such as those of Mercury,
     Venus, and the other stars wandering through the zodiac, or
     about the other solar eclipses from the transit of Mercury or
     Venus, since they are altogether undiscernible to the naked
     eye, and very few compilers of ephemerides wish them to be
     noted, probably for the same reason.

     Do not, however, expect, star-loving reader, that here anything
     at all that you may wish can be drawn forth as from its source,
     for to demand this would be almost the same as to seek to drain
     as from a cup all the vast knowledge of the many arithmetical
     sciences from the narrow confines of one book. You will
     understand how impossible that is when, through prolonged
     labor, you have grown somewhat more mature in this kind of

     Wherefore, rather fully, and out of consideration for you, I
     have decided, setting aside these prolixities, with completely
     synoptic brevity and with all possible clarity to expound for
     you simply the proportion of the movements, the description of
     the machine, and its usage. As a result, when you have
     progressed a little in theoretical mechanics, you will not only
     be able to reduce all these things to their astronomical
     principles, but you may find the way more smoothly laid out for
     you even for perfecting the machine itself. And, thus, you may
     be more effectively encouraged to a successful conclusion. Let
     it be so now for you through the following 10 chapters!

After these rather hopeful assurances, Father Borghesi proceeded to
provide a detailed description of the clock dial and functions in the 10
short chapters which he had promised, under a separate section entitled
"Synopsis Totius Operis Mechanici," which is translated in its entirety
in the appendix.

As Father Borghesi prepared his little volume about his first clock, and
described its unusual features and outlined its functions, which were
primarily to place in evidence the celestial constellations, it occurred
to him that it would now be easier after the experience he had acquired
with his first timepiece, to construct another clock, which would
present the motions of the two astronomical systems, the Ptolemaic and
the Copernican. In this first book, he promised the reader that he would
undertake the second project. It is fortunate that Father Borghesi
undertook this project for the second clock is the only example of his
work that is known to exist today. Extensive research has not shown what
happened to the first clock, although several sources state that both
timepieces were presented to Empress Maria Theresa sometime between 1764
and 1780.

Second Borghesi Clock

Father Borghesi lost no time in initiating the project of the second
clock. The first and most important step was to inform Bertolla and
enlist his assistance. Bertolla was adamant: he had had enough of
complicated astronomical movements. He was delighted by the prospect of
returning to his former simple life, producing simple, domestic,
elementary movements for his country clients. Father Borghesi begged and
cajoled. The second clock would be a much simpler one to construct, he
persisted. After all, they had gained invaluable experience from the
production of the first clock. Furthermore, he had already completed its

Bertolla apparently wavered in his resolve and, unwillingly and against
his better judgment, he allowed the priest's inducements to prevail.
Once again, the two friends yielded their leisure hours to a study of
the priest's books and drawings as Father Borghesi enthusiastically
elaborated his design for the timepiece, and Bertolla attempted to
transcribe astronomical indications into terms of wheel counts. The
second clock was, as Borghesi had promised, much easier of execution.
Within a year, it was completed and functioned with complete success.

[Illustration: Figure 8.--THE BORGHESI CLOCK in the Museum of History
and Technology, constructed in 1764 by Bartolomeo Antonio Bertolla of
Mocenigo di Rumo from the designs of Father Francesco Borghesi of Rumo
and Mechel.]

[Illustration: Figure 9.--ANOTHER VIEW of the Borghesi clock.]

This is the clock now in the Museum of History and Technology. It is
housed in a tall case of dark-red mahogany veneered on oak, with
restrained carving featuring ribands and foliate motifs. Gilt-brass
decorations flank the face of the hood, which is surmounted by three
gilt-brass finials in the form of orbs. A wide door in the waist may be
opened to attend the weights. The case is 7 feet 8 inches high, 20-1/2
inches wide at the waist, and 14 inches in depth.

The dial is of gilt brass, measuring 21 inches high and 15 inches in
width, with a number of supplementary silvered dials visible through its
openings. Instead of hands, the dial utilizes three concentric rings
moving around a central disc, the indications of which are read at two
bisecting gilt lines inscribed in the glass face. Twelve separate
functions are performed by the chapter ring assembly alone, and there
are 14 openings on the dial. It is estimated that the clock performs 30
separate functions, including striking and chiming. Of the multiple
chapter rings, the outermost is 1-1/8 inches wide, the center ring is
3/8 inch wide, and the innermost ring measures 1-1/4 inches in width.


The gilt dial is incised throughout with figures and inscriptions in
engraving of the very finest quality, as is evidenced in the
illustrations. The frontispiece is surmounted at its center by the
crowned double eagle of the House of Hapsburg, indicating the identity
of the sovereign in whose reign it was made, Emperor Francis I or the
Empress Maria Theresa of Austria. Below the eagle at either side are
flying cherubs supporting ribands with inscriptions. Centered at the
bottom of the frontispiece immediately above the chapter rings is the
moving silvered orb representing the sun. Surrounding it is a tableau of
the Holy Trinity, with the Virgin Mary being crowned by Christ holding a
cross at the left and God with a sword in hand at the right, and a dove
representing the Holy Spirit hovering over the Virgin's head. Father S.
X. Winters, S.J., considers it reminiscent of the triptych "The
Coronation of the Virgin" by Fra Lippo Lippi.

[Illustration: Figure 10.--DIAGRAM OF the dial plate.]

[Illustration: Figure 11.--DIAL PLATE of the Borghesi clock.]


A Dominating planet, represented by its symbol and its house;

B Dominical letter (Lit. Dom.);

C Epacts (Cyc. EpEC);

D Roman indiction (Ind. Rom.), part of the reckoning of the Julian

E Solar cycle, (Cyc. Sol.), part of the reckoning for the Julian period;

F Golden number (Num. Aur.), part of the reckoning for the Julian

G, H, I, J The era, or the current year; part of the six windows of the
Iris, or rainbow;

K Shuttered winding hole, for winding up the weights; part of the six
windows of the Iris;

L The era, or the month of the current year; part of the Iris, or six
windows of the rainbow;

M The sun in its epicycle;

N The 12 signs of the sun's anomaly;

O, P The first chapter ring representing the equatorial globe of the
week, revolving from left to right;

Q The coming day indicated through the window;

R The second chapter ring; including the synodic-periodic measure of
the tides, the days of the median lunar-synodic age, the signs and
degrees of the signs for mean distance of the moon from the sun;

S Epicycle of the moon with signs of its anomaly;

T Head of the dragon (Cap. Draconis);

U Tail of the dragon (Cauda Draconis), for measuring eclipses of the
earth and of the moon;

V Third chapter ring, with degrees of lunar latitude and some fixed

W Fourth chapter ring, showing firmament of fixed stars, signs of the
zodiac and degrees of the signs, the months of the year, and days of the
months, revolving left to right for the course of a mean astronomical

X Adjustment marked _Claudit_ (it closes) and _Aperit_ (it opens) for
disengaging dial work for the purpose of making astronomical experiments
and computations;

Y Adjustment marked _Concitat_ (it accelerates) and _Retardit_ (it
retards) for fast and slow adjustments of the movement.

In the upper spandrels of the dial are two more cherubs bearing ribands
with inscriptions. In the lower left corner is a magnificent engraving
of Atlas upholding the globe of the world, inscribed with the zodiac,
over his head. The lower right corner features the figures of two
noblemen apparently examining and discussing an orb upon a table, the
significance of which is not clear.

[Illustration: Figure 12.--EMPRESS MARIA THERESA, to whom Father
Borghesi is stated to have presented his two astronomical clocks. The
coin bearing her portrait is in the Museum of History and Technology.]


Beginning with the uppermost part of the frontispiece, there are nine
inscriptions in Latin on the dial plate. The topmost is _Franciscvs I
sit plan. Dominator aeternvs._ The phrase has reference to Francis I,
who was Emperor of the Holy Roman Empire, from 1745-1765, and husband of
Empress Maria Theresa of Austria. The phrase may be translated as "May
Francis I be the eternal ruler by favor of the planets" or more simply
"Long Live Francis I, Emperor."[14] Although the dial plate of the
Borghesi clock is inscribed with his name, the records indicate that
the clock was presented to Maria Theresa. Francis I may have already
died before the presentation was made.

[Illustration: Figure 13.--PORTRAIT OF FRANCIS I, Emperor of the Holy
Roman Empire, to whom Father Borghesi's astronomical clock in the Museum
of History and Technology appears to have been inscribed.]

From the left to right over the tableau of the Holy Trinity is the
phrase "Lavs sacrosanctae Triadi Vni Deo, et Deiparae" (Praise [be] to
the most Holy Trinity, to the one God, and to the Mother of God).

Within the upper left and right spandrels is inscribed:

     Isthaec, Signum grande apparvit in Coelo * sancta Dei genitrix
     amicta sole * Illibato pede Lvnae et serpentis nigra premens
     Cornva * bis senis pvlcherrime Coronata syderibvs * Tempe
     indesinenter clavsa, scatvrigo signata * Cedrvs in Libano,
     Cypresvs in Monte Sion * Mater pvrae Dilectionis sanctaeqve
     spei * Chara patris aeterni proles, Verbi Mater, sponsaqve
     procedentis *, gratiae et gloriae circvmdata varietate.

This inscription is a eulogy to the Virgin Mary assembled from the texts
of Holy Scripture. In addition, each _lemma_, contained within
asterisks, carries out the chronogram 1764, the year the clock was
completed. Each _lemma_ is translated and identified from the
Douay-Rheims version of the Bible:

     This woman: a great sign appeared in Heaven (Apocalypse 12:1) *
     The Holy Mother of God clothed with the sun (Apocalypse 12:1) *
     And with unharmed foot crushing the black horns of the moon
     (Apocalypse 12:1) and the serpent (Genesis 3:15) * Most
     beautifully crowned with twice-six (Apocalypse 12:1) * A garden
     [_Tempe_[15]] enclosed, sealed with a fountain [spring of
     water] (Song of Songs 4:12) * Like a cedar in Lebanon, and a
     cypress tree on Mount Zion; (Ecclesiasticus 24:17) * Mother of
     pure love and of holy hope: Beloved daughter of the Eternal
     Father, Mother of the Word, Spouse of the Holy Spirit:
     (Ecclesiasticus 24:24) * Surrounded with a diversity of grace
     and glory (Psalms 44:10).

[Illustration: Figure 14.--THE BOTTOM RIGHT CORNER of the dial plate,
showing two noblemen contemplating an orb, with the inscription "Diligit
Avdaces Trepidos Fortvna Repellet." (Fortune favors the daring and
rejects the timid.)]

At the lower left corner below the figure of Atlas upholding the world
is the phrase, _Assidvo proni donant di cvncta labori_. (The favorable
gods willingly grant all things to the assiduous laborer.) The same
phrase is quoted by Father Borghesi in the text of his second volume.
The last inscription appears at the lower right corner under the figures
of the two noblemen, _Diligit avdaces trepidos fortvna repellet_.
(Fortune favors the daring and rejects the timid.) The last two
inscriptions are in dactylic hexameter. They appear to be original
compositions inasmuch as no classical prototypes have been identified.

[Illustration: Figure 15.--THE BOTTOM LEFT CORNER of the dial plate,
showing the engraving of Atlas, with the inscription "Assidvo proni
donant di cvncta labori." (The favorable gods willingly grant all things
to the assiduous laborer.)]


[Illustration: Figure 16.--DETAIL OF FRONTISPIECE of the Borghesi clock,
showing the apertures for calendar indicators and the details of the

In addition to the inscriptions previously noted on the outer dial
plate, there are three major inscriptions in the central dial. The
outermost states _Circulus horarius Soli_, _Lunae_, _Fixis_, _Nodis_,
_Aestuique marino communis_ (the hour circle, common to the sun, the
moon, the fixed stars, the nodes and to the sea tide). This inscription
is divided into four parts by the insertion of four divisions for the
day into canonical hours: [_Horae_] _Nocturnae_ (night hours);
_Matutinae_ (morning hours); _Diurnae_ (daytime hours) and _Vespertinae_
(evening hours).

The next section of the central dial is inscribed
_Intumescite--Detumescite_ (rise and fall of the tides) repeated at
intervals of approximately every six hours. Within the next section is
the following inscription, inscribed continuously around the ring:

     Lege fluunt, refluunt, dormitant hac maris undae: Ad Phoebi et
     Phoebes concordia iussa moventur Aequora; discordi iussu
     suspensa quiescunt.

Translated, this is:

     By this law the sea waves ebb and flow and lie dormant: When
     Phoebus and Diana agree in their commands, the waters are
     moved; when they disagree, the waters lie silent.[16]

Within the central boss of the dial plate, the name of the maker is

     Bvrghesio Doctore, et Bertolla Limatore Annaniensibvs*

Translated, this is:

     [By] Doctor Borghesi and Bertolla, mechanician citizens of


There are 12 windows in the frontispiece, through each of which appears
an indication relating to time. Beginning at the top of the frontispiece
of the dial, the first opening occurs on the breast of the imperial
eagle. This indicates the dominating planet, represented by its symbol,
and its house.

The opening in the eagle's left claw, labeled "Lit. Dom." is the
dominical letter. The first seven days in the month of January are each
assigned one of the letters _a_ through _g_ in order of appearance. The
letter which coincides with the first Sunday within this period is
called the dominical letter, and it serves for the following year. In
leap year, two letters are required, one to February 29th and the letter
next proceeding for the remainder of the year. This letter is used in
connection with establishing the date of Easter Sunday. The date of
Easter regulates the dates of the other movable feasts.

The eagle's right claw is labeled "Cyc. EpEC" and represents the epact,
or the age of the moon on January 1st. It serves to find the moon's age
by indicating the number of days to be added to each lunar year in order
to complete a solar year. Twelve lunar months are nearly 11 days short
of the solar year, so that the new moons in one year fall 11 days
earlier than they did the preceding year. However, 30 days are deducted
as an intercalary month since the moon has made a revolution in that
time, and the remainder, 3, would be the epact.

Below the imperial eagle two winged cherubs support a riband with three
indictions of the Julian period. This period of 7980 years is the
product derived from multiplying together the sums of 28, which
represents the cycle of the sun; 19, representing the cycle of the moon;
and 15, which represents the Roman indiction. The Julian period is
reckoned to have begun from 4713 B.C. so that the period will be
completed in A.D. 3267. The first of the three openings is marked "Ind.
Rom." or "Roman indiction," which was an edict by the Emperor
Constantine in A.D. 312, providing for the assessment of a property tax
at the beginning of each 15-year cycle. It continues to be used in
ecclesiastical contracts. The second opening, which occurs immediately
below the eagle, is marked "Cyc. Sol." (cycle of the sun). This cycle
takes a period of 28 years, after which the days of the week once again
fall upon the same days of the month as they did during the first year
of the former cycle. There is no relationship with the course of the sun
itself, but was invented for the purpose of determining the dominical
letter which designates the days of the month on which the Sundays occur
during each year of the cycle. Since cycles of the sun date from 9 years
before the Christian era, it is necessary to add the digit 9 to the
digits of the current year and then divide the result by 28. The
quotient is the number of cycles which has passed, and the remainder
will be the year of the cycle answering to the current year. The third
opening on the riband is labeled "Num. Aur." (golden number). Meton, an
astronomer of Athens, discovered in 432 B.C. that after a period of 19
years the new and the full moons returned on the same days of the month
as they had before, and this is called the cycle of the moon. The Greeks
were so impressed with this calculation that they had it inscribed in
letters of gold upon stone, hence the golden number. The First Council
of Nicaea in A.D. 325 determined that Meton's cycle was to be used to
regulate the movable feasts of the Church.

Immediately above the chapter rings is an opening through which the orb
of the sun is visible.


In a separate chapter in his second volume, entitled "Descriptio
Authomatis Summa totius Operis Mechanici" (Description of the
Automaton--Summary of the Complete Mechanism), Father Borghesi provided
a description of the functions of the various indicators, prefixing it
with the short poem shown in figure 18. He then continues:

     In the middle of the frontispiece, as at the center of the
     universe, the terraqueous globe of the week revolves, with a
     daily motion turning from right to left, bringing with it from
     the round window the coming day and at the circumference the
     circle of hours common to the sun, to the moon, to the fixed
     stars, to the head and tail of the dragon, and to the raging

     The second circle revolves the synodic-periodic measure of the
     raging sea, the days of the median lunar-synodic age, the signs
     and individual degrees of the signs of the distance of the moon
     from the middle of the sun within the time of 29 terrestrial
     revolutions, hours This circle revolves likewise
     from right to left around the center of the earth. In this
     second circle, another little orb revolves, bringing with it
     the epicycle of the moon, in which the little circle of the
     moon (whose illuminated middle always faces towards the sun),
     running from left to right through the signs of the anomaly;
     within 13 revolutions of the earth, hours 18.39.16. It descends
     from apogee to perigee and in just as many others it returns
     from perigee to apogee, to be carried down thus to true, back
     and front from the longitude and distance from the sun and from
     the middle of the earth.

     The third circle (on which I have tried to indicate
     astronomically-geometrically in their places, the degrees of
     lunar latitude both in the south and in the north, and some
     fixed stars, those, namely, which can be separated by us from
     the moon which goes between) from left to right turns around
     the center of the earth, stretching out the head and tail of
     the dragon, on the inside above the second circle for noting
     and measuring the sun (but I should rather say the earth), and
     the eclipses of the moon, within 346 revolutions of the earth,
     hours 14.52.23.

     The fourth circle, in which the heaven of the fixed stars,
     reduced to the correct ascent of our times, the signs of the
     zodiac and the individual degrees of the signs, the months of
     the year and the single days of the month can be seen, likewise
     makes its journey around the earth from left to right in 365
     terrestrial revolutions, hours 5.48.56.; that is, within a
     median astronomical year. Above this annual orb, the sun, in
     its small epicycle, gliding through the 12 signs of the
     anomaly, within the space of 182 terrestrial revolutions, hours
     15.6.58., from left to right, falls from apogee to perigee;
     and, within the same time, rises from perigee to apogee, and
     brings with it, the index, namely its central radius, inhering
     to the axis of the equatorial orb and cutting the four greatest
     circles from the center.

     When the sun has been moved around, Iris shows from six windows
     the era, that is, the current year. Two winged youths take
     their place next to Iris, carrying the Julian period: namely,
     the Roman indiction, the cycle of the sun and the golden
     number, on a leaf of paper held between them. The imperial
     eagle stands out on top (as if added to the frontispiece)
     carrying on its breast the dominating planet and in its talons
     the ecclesiastical calends (that is, the dominical letter and
     the epact).


Two attachments, in the form of small superimposed dials are situated at
the base of the dial plate, at either side and immediately below the
fourth chapter ring. In his second volume, Father Borghesi stated that
they "are not moved from inside the clock, but the one at the right
[inscribed _concitat_ and _retardat_] serves for loosening
[accelerating] and tightening [retarding] time; that is, the reins of
the perpendicular."

In other words, the purpose of this attachment is for adjusting the
pendulum to make the clock operate fast or slow. The second attachment,
which appears at the left, and which is inscribed "Claudit" (close) and
"Aperit" (open) serves the purpose of "... preparing the mechanism in a
moment, as swiftly as you wish, for sustaining the astronomical
experiments of which you will hear later; when these things have been
done, it restores the mechanism to its natural motion at the same

This adjustment relates to the final section of Father Borghesi's second
book, entitled "Chronologo-Astronomicus Usus Authomatis"
(Chronological-Astronomical Use of the Automaton), which is translated
from the Latin in its entirety:

     With one glance at this automaton, you can quickly answer these
     questions: What hour the sun shows, the moon, any fixed star,
     the head and tail of the dragon. Is the sea swelling with
     periodic heat [at high tide?] or is it deflated [low tide], or
     quiescent? How many days is it from mean new moon or full moon?
     By how many signs and degrees is the moon distant from the sun,
     and from its nodes? What sign of the zodiac does the sun
     occupy, the moon, the head and tail of the dragon? Is the sun
     or the moon, in apogee or perigee, ascending or descending?
     What is the apparent speed of the sun and of the moon? What is
     the apparent magnitude of the solar and lunar diameter, and of
     the horizontal parallax of the umbra and penumbra of the earth?
     What is the latitude of the moon? Is it north or south? Does
     the moon hide [occult eclipse] any of the fixed stars from the
     earth dwellers, and which of these does it obscure? Is there a
     true new or full moon? Is the sun in eclipse anywhere on earth?
     What is the magnitude, and the duration of this eclipse, with
     respect to the whole earth? Can it be seen in the north or in
     the south? Is the moon in eclipse? Total or partial? Of what
     magnitude, etc.? What limb of the moon is obscured? How many
     years have passed from a given epoch? Is this year a leap year,
     or a common year--first, second, or third after leap year? What
     is the current month of the year, and what day of the month and
     of the week? Which of the planets is dominant? What days of the
     year do the various feasts fall on, and the movable feasts
     during the ecclesiastical year? And many other similar
     questions, which I pass over here for the sake of brevity.

     Besides, this device can be so arranged for any time
     whatsoever, past or future, and for the longitude of any
     region, and can be so manipulated by hand, that within the
     space of a very short time there can be provided in their
     proper order, the various orbits of the luminous bodies, their
     alternating eclipses, as many as have taken place through the
     course of many years, or even from the beginning of the world;
     or those that will be seen as long as the world itself shall
     last, with all their attendant circumstances (year, month, day,
     duration, magnitude, etc.). All these can be seen with great
     satisfaction of curiosity and of learning, and hence with great
     pleasure to the soul. In the meanwhile, the little bells
     continually play, at their proper, respective times. So that,
     all exaggeration aside, a thousand years pass, in the sight of
     this clock, as one day!

     I am aware of your complaints, O star-loving reader--that my
     description is too meager and too succinct. Lay the blame for
     this on those cares, hateful both to me and to you, more
     pressing, which forbid me and deprive you of a methodical
     explanation of the work.


Father Borghesi specified that the entire mechanism was equal in weight
to a seventh part of a _Centenarii Germanici_, a Germanic hundredweight.
This is probably the Austrian centner which is equivalent to 123.4615
pounds. Therefore, the clock mechanism weighs approximately 17.6 pounds.

The clock operated for a hundred days and more at a single winding,
according to Father Borghesi, and by means of a pendulum with a leaden
bob weighing 60 Viennese pounds, attached at a height of 5 feet. Father
Borghesi stated the weight of the pendulum to be 60 _librarum
Viennensium_, but the Viennese libra does not appear among the weights
of the Austrian Empire. However, using the average libra, an ancient
Roman unit of weight equal to 0.7221 pound, it may be assumed that the
driving weight should be approximately 45 pounds.

Father Borghesi, however, does not venture to provide any description
whatsoever of the movement of his second clock in his book. He gave the
following reasons:

     But beyond this, I entirely omit [a description of] the further
     apparatus of the very many wheels, etc., inside the clock which
     carry on its functions, lest I become too verbose for some
     persons. To explain more thoroughly the internal labyrinth of
     the entire mechanism, from which the movement of the circles or
     heavens, etc., are derived, would seem to entangle in too many
     complicated perplexities.... Therefore, that I might not delay
     longer, and perhaps to no purpose, I have thought it better to
     leave the whole work to the proportionate calculus of the
     arithmeticians and the technical skill of mechanics. If they
     have any desire to construct a similar mechanism, they will
     follow the aforesaid motions of the heavens, etc., not only by
     one means alone but by many, more swiftly through thoughtful
     study than by any amount of instruction.

     For whoever is well versed in the theory of calculus and sets
     to work at any given project, will discover any desired motion
     by a thousand and more ways, by one or another gearing of
     wheels; which an industrious mechanic will carry out in
     actuality and without too much difficulty. Nor is there any
     reason for anyone to be discouraged, so long as he is not
     disgusted by the amount of labor for there is nothing truer
     than the old saying "The favorable gods grant everything to the
     assiduous laborer."

     Nay, further, even this little work itself can be improved on
     and surpassed by new inventions. Otherwise that other old
     adage, almost as old as the world, would prove false, "What you
     have found already done, you can easily repeat, nor is it
     difficult to add to what has already been invented." Relying on
     this principle, I have already conceived some new things to be
     added to the present little work.

[Illustration: Figure 17.--MOVEMENT OF BORGHESI CLOCK viewed from the
right side, with details of chiming mechanism.]


There is a discrepancy between Father Borghesi's written description in
his second book of the number of bells and those which currently exist
in the clock. At the present time, there are two sets of bells attached
to the upper part of the movement. While Father Borghesi indicated that
there were two sets of bells in the clock, he described the first set by
stating that:

     ... there are three bells inside the clock: The largest, when
     struck by a little hammer at each mean new moon, signifies the
     new moon. The smallest indicates in the same way the full moon
     at the time of the mean full moon, by automatic sound. When on
     the equatorial earth, the sun appears anywhere in eclipse, two
     bells (the largest and the medium) sounding together
     automatically, announce that eclipse at the time of the mean
     new moon. (I think it is evident that eclipses of the sun occur
     at new moons and eclipses of the moon at full moon.)

     When the moon is eclipsed, the smallest and the medium bells,
     simultaneously and automatically, announce the event to the ear
     at the time of the mean full moon. Besides, at the proper time
     and automatically, the largest of these bells announces the
     current solar hour and the smallest bell strikes the quarter

In the clock today, the first set consists of a smaller bell fixed
within a larger one. It is presumably these bells that indicate the
eclipses and also strike the hours and quarter hours. A pull cord
attached to the striking mechanism repeats the current hour and quarter
hours at will. The second set consists of nine meshed bells struck with
individual hammers operated by means of a pinned cylinder as in a music
box. On the hour, the chimes play one of two melodies, which may be
changed at will. While not identified, these appear to be Tyrolean folk
melodies. The largest of this set of bells is dissimilar to the other
chimes, and may be the third bell described by Father Borghesi to
signify the new moon.


One of the most curious aspects of the second clock produced by Father
Borghesi and Bertolla, as well as of the second published volume, is the
presence of chronograms which occur repeatedly on the clock dial and
throughout the _Novissimum Theorico-Practicum Astronomicum Authoma_ from
the title page to the end of the book. Interestingly enough, Father
Borghesi did not utilize this device even once in his first little book.

[Illustration: Figure 18.--A CHRONOGRAM in the text of Father Borghesi's
second volume, indicating the year 1764. The poem is translated as: "In
the Mount of 'Anáuni,' the inscrutable heavens are led, You learn from
these all the labors of the sun and the moon. Here you are shown and
hear the conjunction of the moon: And a bell brings to the ears by its
sound, all eclipses."]

Webster defines a chronogram as an inscription, sentence, or phrase in
which certain letters express a date or epoch. The method used by Father
Borghesi for forming chronograms was a simple one. He used combinations
of uppercase and lowercase letters in two sizes in the inscriptions on
the clock dial and in his writings. At first this curious combination in
the inscriptions on the dial plate was a source of considerable
speculation. The extremely fine quality of the engraving and artistry
was such that these combinations could only be deliberate in nature and
not the accidental whims or accidents of the engraver. Accordingly, they
must be chronographic in intention. Such proved to be the case.

Borghesi used the larger size of uppercase letters to form the
chronogram, and each chronogram was complete within a phrase or line. He
accomplished this by using for this purpose those letters of the
alphabet which form the Roman numerals. The uppercase letters found
within words are copied off in the order in which they appear in the
inscription or phrase. These are then converted into their numerical
equivalents, and totaled. Taking the uppermost inscription on the clock
dial as the first example:

    FranCIsCVs I sIt pLan. DoMInator aeternVs

The letters which are intended to form the chronogram are:

     C  I  C  V I I  L  D    M  I V

    100 1 100 5 1 1 50 500 1000 1 5

These figures added together total 1764.

The second inscription on the clock dial which forms a chronogram is

    LaVs saCrosanCtae TrIaDI VnI Deo, et DeIparae

     L V  C   C  I  D  I V I  D   D  I

    50 5 100 100 1 500 1 5 1 500 500 1 = 1764.

The third inscription required a little more planning, because of its
greater length. Accordingly, Father Borghesi divided it into nine parts,
each of which is separated from the other by means of asterisks. Each of
the nine parts of the inscription formed a chronogram which, in every
instance, totals to the date 1764, the year in which the second clock
was completed. The same procedure was followed with the inscriptions in
the lower left and the lower right corners of the dial as well as with
the maker's inscription within the central disk. This inscription is

    BVrghesIo DoCtore, et BertoLLa LIMatore AnnanIensIbVs

    V I  D   C   L  L  L I  M   I I V

    5 1 500 100 50 50 50 1 1000 1 1 5 = 1764.

The inscriptions within the chapter ring are not utilized for
chronograms, however. It is apparent that Father Borghesi was required
to make a most careful selection of the texts for his inscriptions in
order that none of the phrases included any additional letters which
formed Roman numerals than would total to the date he desired to
indicate, namely, 1764. Where it was necessary, he employed an asterisk
to separate parts of texts so that each would produce the same total.
Any letter that did not form a Roman numeral, even if capitalized or
used in a larger size, did not interfere with the formation of the

In spite of his ingenuity in designing a text which would include only
such of the letters representing the Roman numerals which would provide
the chronograms for 1764, Father Borghesi experienced some difficulties,
particularly in place names. He accordingly changed them in order to
avoid the inclusion of letters that would have disturbed his totals.
Examples are MEGGL instead of MECHL, which had an extra C, and RVNNO
instead of RVMO, which had an extra M.


When the clock had been completed and proved to work successfully,
Borghesi once more reduced a description of the clock and its function
to published form in a second little volume published by Monauni. This
second work was also in Latin, the title of which is translated as _The
Most Recent Theoretical-Practical Astronomical Clock According to the
Equally Most Recent System of the World_. As with his first book, Father
Borghesi devoted a number of pages to a preface addressed to the reader,
which is translated from the Latin:

     This mechanical instrument was far from being ready for public
     notice. A great deal of time and work remained to produce a
     machine of this new system from the very foundations; then, by
     a most accurate calculation to bring the motions of many wheels
     up-to-date with the most recent astronomical observations; and,
     finally, to fashion it with the craftsman's file, often enough
     with a weary hand. All this work I had performed eagerly, so
     that, while in my room, I might contemplate leisurely, both day
     and night, the true face of the heavens and the seas unobscured
     by clouds, even though I had no astronomical equipment. But,
     then I remembered that, in my book on the first clock, I had
     promised a description of a new (at least, as far as is known
     to me) clock. Moreover, friends with astronomical interest, who
     took part in the oft-repeated astronomical experiments
     concerning this clock, persuaded me that the intellectual world
     would enjoy having a greater knowledge and a description of
     this work. However, it was not only the promises nor the
     desires of many which moved me to write this work, but I also
     thought it was necessary to set forth, before the description
     of the clock, an exposition of the astronomical system
     according to which this clock was constructed, so that the
     complete work would be evident to all. I was concerned about
     making this timepiece more acceptable and more understandable
     to those people who are far distant and unable to see it, so
     that this present exposition would obtain credulity among all.
     I could find no better method than to set forth for the reader
     the theory of the universe which I figured out after many
     sleepless nights.

     In testing this theory day after day, it not only appeared to
     be complete, and true, but each day it appeared more
     conformable to reality; it captured my mind in such a way that
     I finally adhered to it. I desired, while I lived, to erect
     this work as a monument to the theory. To do this, I digressed
     a bit from the true-to-life pattern to the mechanical order so
     that I could transfer all the movements of the heavens, etc.
     (which I enjoyed thinking about more), to the plane surface of
     the clock's face. In this way, the ecliptical spectacles of the
     stars, etc., would appear at their proper times clearly before
     the eyes of the viewer. I could also avoid many difficulties
     which otherwise, perhaps, even the hands of the most skillful
     craftsmen could never solve.

[Illustration: Figure 19.--MOVEMENT OF THE BORGHESI CLOCK, viewed from
the rear, showing rear of dial plate.]

[Illustration: Figure 20.--TITLE PAGE of Father Borghesi's second
book. The translation in its entirety is: "The Most Recent
Theoretical-Practical Astronomical Clock According to the Equally Most
Recent System of the World. Author: Francesco Borghesi of Mechel of
Anáuni * Priest of Trent, Doctor of Philosophy * (The System of the
Clock) Ingeniously connected to new theoretical laws published 1764: and
the constructor, Bartholomeo Antonio Bertolla of Rumo, similarly from
Anáuni * who skillfully produced this work * in this same current year
of Our Lord * which is the year 5713 [sic] since God created this earth.
(Trent: From the Printshop of Giovanni Battista Monauni, With Permission
of the Superiors.)" (_Title page reproduced by courtesy of the
Biblioteca della Citta di Trento._)]

     You ought to know, therefore, that as a result of my nightly
     meditations, I have rejected, after much consideration, all the
     explanations of the universe thus far published. All other
     theories of the make-up of the universe, however admirable, and
     however many there are, turn the sun and earth around in an
     ecliptic in an annual movement. Thus, Philolaus was the first
     to move the earth from the center of the universe and move it
     through the void; afterwards, Aristarchus of Samos and then
     Copernicus moved the earth with the moon. The Egyptians, as
     well as Pythagoras, Ptolemy, Tycho, Riciolus, Longomontanus,
     etc., thought that the sun moved through the degrees of the
     ecliptic each year. But I attributed this movement to neither
     earth nor sun for the movement of both is only apparent. I did
     not vainly surmise the annual equilibrium in all astronomical
     observations to be from the daily movement of the same axis
     moved at the poles of the heavens. Nor, in like manner, is
     there a better way to satisfy physical experiments. To you,
     then, most cultured reader: If you, perhaps, can make any use
     or draw pleasure from this most faithful description of my new
     theory and the mechanical instrument, refer it first to God on
     High from whom is everything that is best, and then to those
     avidly awaiting this little work. Lastly, if you find any
     statement less fitting; in your humanity, do not disdain to
     excuse it.

Borghesian Theory of the Universe

In Father Borghesi's second volume, there is a separate chapter entitled
"An Exposition of the Latest Theory of the Universe." This follows the
introduction to the reader, and in it Father Borghesi proposed:

     That you might rightly conceive my new system of the world and
     mechanically, as it were, construct it, imagine for yourself,
     beneath that most happy seat of the Blessed and above all other
     heavens, a kind of spherical convexity, everywhere equidistant
     from the center of the earth, and endowed with absolutely no

     On the inside, at two points diametrically opposite each other,
     this convexity has two most sturdy poles (to speak
     mechanically), projecting towards the center (which you call
     the poles of the heavens), and the largest immobile semicircle,
     in some manner is drawn from the center of one pole to the
     center of the other. This semicircle in the middle, namely at a
     point equidistant from each pole, is thought to be secured by
     some sign, for example, by that "o," for arranging more
     perceptibly the seat of the sun (as will be shown later). This
     much must be conceived first.

     You must understand that imposed on these poles is the first
     mobile [Primum Mobile], everywhere convex, and divided, into 12
     equal parts [Dodecatemoria], by the 6 greatest circles,
     intersecting each other at the centers of the poles. Then it is
     divided by another equally great circle, everywhere equidistant
     from the poles, into two hemispheres. One hemisphere of 12
     parts, proceeding in order from west [setting] to east [rising]
     should be assigned the respective signs of the zodiac; that is,
     one to Aries, the next to Taurus, and so on, etc. The circle
     which cuts those 12 parts transversely in the middle, you call
     the ecliptic. Then, these capital spaces of the Primum Mobile
     are subdivided by degrees, minutes, etc., both in longitude and
     in latitude, so that this heaven represents a kind of great
     spherical net, extended to capture the longitude and latitude
     of the stars, and Mobile on the aforementioned poles. Note,
     however (and this is almost the leading point of the system),
     in that circle of longitude which divides the sign of Gemini
     from Cancer and Arcitenens [Sagittarius] from Capricorn, you
     must conceive two points, directly opposite each other and
     removed about twenty-three and a half degrees from the poles:
     Boreal [the northern] between Gemini and Cancer; Austral [the
     southern] between Sagittarius and Capricorn. These two points
     by some power (imagine it is magnetic power), equal between
     them, hold the terraqueous orb suspended in the middle, by
     acting on the axis of the same orb (imagine it is iron) in such
     a way that the earth is continually drawn to those two points
     as to two opposite centers. It is never nearer to one, for as
     it is about to move towards one, the opposite power is
     constantly drawing it back. Thus, both those points and the
     axis of the earth are always held in one common line, wherever
     those points happen to be carried by the rotation of this

     Again, it is necessary for you to conceive in this heaven,
     first, two great circles, bisecting each other at right angles
     in the centers of these two magnets. One of these circles,
     passing through the first point of Aries and Libra in the
     ecliptic, is called equinoctial colure: the other circle,
     passing consequently between the first point of Cancer and
     Capricorn, is called solstitial colure. Beneath these are
     likewise imagined many other great circles, in the centers of
     the magnets dividing crosswise in the shape of an "X." But if,
     receding from these magnets, you describe circles (parallel to
     each other and ever greater and greater, up to the greatest
     circle which you will perceive is called the equator),
     equidistant from each magnet and obliquely splitting the
     ecliptic in the equinoctial colure, you can then behold a
     great, new, woven net in this heaven of the Primum Mobile. This
     net most beautifully expands to extract the straight ascent and
     descent of the stars, etc., from the vast ocean of the heavens,
     catching the straight ascent in the greatest circles and, in
     other unequal circles, parallel to each other and obliquely
     cutting across, most safely catching the descent.

     Immediately below the Primum Mobile place the heaven of the
     fixed stars (and, that the idea might be clearer), revolving
     separately on the same poles on which the Primum Mobile
     revolves. Through this heaven, the filaments of the little
     nets, etc., seem to the eyes of you on earth as if they shine.
     In this heaven, you should conceive in their fixed places, the
     fixed stars, a proportionate, inviolable distance from each
     other, and, indeed, if you will, the heavenly images, etc.,
     depicted, and all carried along at the same time with their
     heaven by one motion.

     Conceive a straight line running from the center of the earth
     to that sign "o" noted in the semicircle of the supreme
     immobile heaven. On this line, greatly below the heaven of the
     fixed stars, place the center of the solar epicycle, holding an
     area in common with the ecliptic and subject to absolutely no
     motions, but at such a distance from the center of the earth
     that the semidiameter of the earth has little, if any,
     proportion with the distance of the solar epicycle from the
     earth. Around the sun, moving continually in this epicycle (its
     immobile palace) through the degrees of the anomaly, you can
     revolve, with motions proportionate to the system, the five
     planets: Mercury and Venus (the nearest barons of the sun),
     then Mars, Jupiter and, most remote, Saturn, with its
     respective satellites, etc., eccentrically surrounding the
     earth itself and the moon in their immense ambit and wandering
     by their proper motions through the zodiac.

     Nevertheless, not far from the earth you should imagine
     fabricated, as from most refined crystal, the heaven of the
     moon everywhere equidistant from the center of the earth and
     revolving separately on the same poles (prolonged even to this
     place) on which the Primum Mobile and the heaven of the fixed
     stars revolve. In the middle of this, that is, in some point
     equally removed from the poles, you place the center of the
     lunar epicycle, movable also by the common rotation of the
     lunar heaven. I refrain from the other movements of the moon in
     latitude, etc., as also those of the five planets, etc., which
     the theory in no way excludes, lest by a variety of congested
     motions explained too abundantly, either you might be confused
     about the fundamental concept of the system or, while adorning
     the theory and trying to embellish the least things more
     widely, you might reject also the things which are capital.

     Here you already have the whole machine, but still inert and to
     be animated for the first time by motions accommodated to the
     system. Nevertheless, before I assign motion to the individual
     parts of the world, so that the thing might later appear more
     clearly to you, I arrange all things thus: first, as if by
     hand, I turn the Primum Mobile until the Boreal magnetic point
     comes to the level or the area of the semicircle described in
     the supreme immobile convexity; then I turn the heaven of the
     fixed stars until, for example, the heel of Castor (a star of
     the third magnitude), almost in the ecliptic and indeed in our
     time not far distant from the solstitial colure, likewise falls
     nearly at the level of the aforesaid semicircle. Later, I turn
     the lunar heaven until I bring the center of the lunar epicycle
     to the same level. Then, I turn the earth until some
     predetermined city, for example, Trent, situated in the
     northern zone with a latitude of about forty-six degrees, is
     brought to the oft-mentioned level.

     From things arranged in this way and from what has gone before,
     it is evident (with the motions of the luminaries in epicycles
     left out, however, lest you be distracted by the explanation)
     that at Trent, just as in the whole northern hemisphere, it is
     the summer solstice; and, conversely, in the southern
     hemisphere, it is the winter solstice. The reason is because
     the northern magnetic point together with the northern half of
     the earthly axis is at its highest point towards the sun,
     immovably residing in a line sent through the level of the
     highest semicircle; and, conversely, the southern magnetic
     point with the corresponding half of the axis is most removed
     from the same. It further follows, that noonday and the new
     moon coincide, and the heel of Castor almost reaches the
     summit, etc.

     Now, beginning from this hypothetical situation of the whole
     world as from the root of the motions, I move all things in
     their circles so that the earth turns on its axis with a
     revolving motion from west to east in each 24 hours of median
     time. The lunar heaven completes one circle around its poles
     likewise from west to east in the time of 29 terrestrial
     revolutions, hours The sphere of the fixed stars
     on the same poles revolves once from east to west within 365
     revolutions of the earth, hours The Primum Mobile on
     the poles (common to the heaven of the fixed stars and the
     heaven of the moon), is moved once in the same way from east to
     west, a little faster, however, than the heaven of the fixed
     stars, yet within 365 revolutions of the earth, hours 5.48.56;
     that is, within a median astronomical year.

     Now, behold for yourself a new world supported on new poles and
     provided with new motions and laws. Now you, reader and lover
     of the stars, turn it, and revolve it as long as it pleases
     you, and compare it astronomically and physically with the
     Copernican or the Tychonian systems or with whatever one
     pleases you more, and judge which one seems more consonant with
     nature when all things are examined. But if you aren't able to
     reconcile this theory with some astronomical observations or
     physical experiments and think it should be eliminated from
     the group of theories, see that I might know this while life is
     still my companion, so that I might think with you, if this is
     possible. Also, so that, in gratitude for the detected or
     perhaps hidden error, I might speak or write, and you won't
     have to shout in vain in bold ridicule and with no applause
     after the fleeing shades of the dead and the mute ashes. But,
     if you object that the daily motion of the revolving earth and
     the annual motion of its whirling axis do not sufficiently
     agree with certain texts of Sacred Scripture, and if those
     things which the Copernicans and the Longomontanists say do not
     convince you, then reject my whole system as an old wives'

       *       *       *       *       *


ANOMOLIA or anomaly, is the angular distance of a planet from its
perihelion (that point of the orbit of a planet which is nearest to the
sun) as seen from the sun.

AEQUINOCTIUM or the equinox, is the time in which days and nights are
equal in the space of hours. There are two equinoxes: the spring
equinox--c. 8 calends of April in the sign of Aries; and the fall
equinox--c. 10 calends of October in the sign of Libra.

AERAS is derived from _aera_, _aerae_, which originally meant a given
number, usually used in regard to money. The word was later extended to
mean a number used in any calculation, and finally it came to mean a
certain time from which subsequent times were counted, e.g., _Anno
Domini_, after the Birth of Christ.

COLURI or the Colures, which are two circles in the heavenly sphere,
passing through the poles of the world and cutting each other at right
angles: the one passes through the equinoctial points of Aries and Libra
and is called _Colurus Aequinoctiorum_ or equinoctial colure; the other
touches the _solstitialia_ of Cancer and Capricorn and is called
_Colurus Solstitiorum_ or solstitial colure. They are called _Colurus_,
which is translated as "mutilated tails," for the part which emerges in
the Antarctic is not visible and is quasitruncated.

ECLIPTICA or the ecliptic, is an imaginary line in the heavens in which
the sun was supposed to have performed its annual course.

EPICYCLUS or epicycle, is a small orb which, being fixed in the deferent
of a planet, is carried along with its motion and yet, with its own
peculiar motion, carries the body of the planet fastened to it round
about its proper center.

IRIS or the rainbow. In mythology, Iris was the daughter of Thaumatis
and Electra, messenger of Juno of the goddesses and Jove of the gods.

SOLSTITIUM or the solstice, is that time when the sun seems to stand
still for a short time: when the sign of Cancer enters the month of June
(equivalent to the summer solstice, when the sun begins to recede from
us); and when the sign of Capricorn enters the month of December
(equivalent to the winter solstice, when the sun begins to accede to

       *       *       *       *       *

Last Years

There is a break in the story of Borghesi and Bertolla for the next five
years. The second clock may have been the last project on which the
priest and the clockmaker worked together, for very good reasons. The
two clocks must have represented a considerable financial investment in
materials and in time, and neither of the men was in sufficiently
affluent circumstances to undertake the luxury of such a hobby without
some form of recompense. The publication of the two little volumes must
have also been done at Father Borghesi's expense. The income of the
parish priest in a small mountain village could not have been equal to
the relatively great costs of the projects that had been completed. It
seems probable that the priest attempted to sell his clocks to a wealthy
patron, perhaps the Baron of Cles, or he may have attempted to obtain
some form of recompense for the continuation of his research. However,
no records can be found of such patronage if it existed. If Borghesi had
received financial assistance while the projects were in progress, he
would certainly have made adequate mention of the patron's name and
assistance in one or the other of the two volumes which he

The next record relating to Borghesi which has been found is the
description of a letter written by an anonymous mathematician late in
1768 or early in 1769. It was 28 pages in length, written in Latin, in
the form of a reply to the writer's brother, on the subject of the clock
invented by Borghesi. It consisted primarily of a criticism launched
against Borghesi's first little volume published in 1763.

The anonymous letter is without date, place, or signature. This writer
claimed that Father Borghesi had made many errors in his book,
presumably in the description of the clock's functions, and in the basic
theories upon which the priest had predicated his research. No complete
copy of the letter's text has been found for study, although it is
described at length in Tovazzi's _Biblioteca Tirolese_. Tovazzi noted
that four copies of the letter existed at that time, and that he
personally had filed one in the Biblioteca di Cles in Trent. However,
every attempt to locate a copy at the present time has been

If the anonymous letter was brought to the attention of Father Borghesi,
it must have introduced a disturbing note into his life and cost the
priest many unhappy moments. He was not, however, dissuaded from his
preoccupation with horology. Several years later, in 1773, Father
Borghesi was working on yet another astronomical clock, this time
presumably without the assistance of Bertolla. This third clock was
reported by Tovazzi to have been "of minimum expense but of maximum

No subsequent information relating to it has come to light, and there is
no record that it was actually completed.

Again there is a period of silence in the life of Father Borghesi which
no amount of research has yet been able to pierce. Whatever the
circumstances may have been, it is reported by several of the sources
noted that both the first and the second clock did, in fact, become the
property of the Empress Maria Theresa in Vienna. The presentation was
made sometime during the period between the completion of the second
clock in 1764 and the year 1780. There is some discrepancy in the
contemporary accounts as to whether Father Borghesi presented one or two
clocks to the Empress, but all the sources with but one exception record
that both clocks were acquired by the Empress.

It is doubtful that Father Borghesi had originally intended to give his
clocks to the Empress at the time that they were made, for he would most
certainly have made some mention of such an intention in the two little
volumes which he published about them. If he saw the letter published by
the anonymous mathematician in late 1768 or 1769, it is possible that he
decided to make the presentation in expiation of his sense of guilt for
the amount of his time which the creation of the timepieces had
consumed. On the other hand, it is just as possible that Father Borghesi
may have forwarded copies of his two little volumes to the Imperial
Court at Vienna, and that the Empress expressed a desire to acquire the

Father Tovazzi states that in 1780 "the clock invented by him [Borghesi]
was preserved in Vienna, Austria, at the Imperial Court from which the
inventor was receiving an annual pension of 400 florins." No records in
the Palace archives relating to the clock have yet been found, nor
records of payment of an annuity to Father Borghesi. However, a more
exhaustive investigation of the Furniture Depository of the Imperial
Court may bring forth related records. It was the implication in Father
Tovazzi's account that the second clock had been presented to the
Empress prior to the publication of the anonymous, critical letter in
1768 or 1769. He believed that it was envy of Father Borghesi's
ingenuity, fame and financial benefit that had caused the anonymous
mathematician to publish his letter, for Tovazzi asked "Who would have
encountered opposition to such a marvel? Envy is not yet dead, and has
always reigned."

This last-mentioned theory about the presentation may be the most likely
one. Some evidence may be found in the second clock itself which bears
out this assumption. The multiple chapter ring, with its many
inscriptions, is engraved and silvered in a relatively crude manner,
presumably by Bertolla himself. The main dial plate, however, which is
of gilt brass, is engraved with the utmost skill by one of the great
masters of the art. The inscription below the Imperial Hapsburg eagle
relates to Francis I, Emperor of the Holy Roman Empire. It is entirely
possible that although Father Borghesi originally had no intention of
giving the clock to the Emperor or the Empress at the time that it was
made, he later changed his mind. Accordingly, he may have commissioned a
master engraver, possibly in Trent or in Vienna itself, to produce a
dial plate which would be of such a quality as to be worthy of the
Emperor himself. If so, this was done shortly after the clock was
completed, for the Emperor died in August of the following year. Perhaps
by the time that the clock was ready, the Emperor had already died, and
Father Borghesi gave the clock instead to Maria Theresa without revising
the inscription.

The acceptance of the clocks by the Empress, and the annuity which was
his reward, would have constituted considerable honor even for one of
the foremost clockmakers of the Empire, but for a humble parish priest
in a little village, such notable Imperial recognition was overwhelming.
Possibly as a result of it, a change was noted in Father Borghesi in the
next few years. His conscience began to bother him, and he began to
question whether he had done right in spending so much of his time and
thought on his horological research. He became more and more confused in
his own mind. Had he spent too much time in mechanical studies to the
neglect of his ecclesiastical duties? If this had been the case, he had
committed the most grievous sin.

Exaggerated though these thoughts may appear, they were undoubtedly of
the most critical importance to the middle-aged priest. His mental
turbulence and confusion increased daily, and it soon became apparent to
others around him. By June 1779, he was completely in the grip of his
obsession, and his parishioners began to whisper amongst themselves that
their pastor was being tortured by the devil. They were unable to help
him, and he became more and more preoccupied with his problem. The years
passed slowly as the pastor became more vague and more tortured by his

There probably was continued contact between Father Borghesi and
Bertolla for at least some time after the development of his illness.
Bertolla had retired from active work, but continued to pursue his
interests in his clockshop as much as his health and advanced years
permitted. A clock which he made at the age of 80 survives and is
described and illustrated in the following section on "The Clocks of
Bartolomeo Antonio Bertolla." Finally, on January 15, 1789, Bertolla
passed away and Father Borghesi was left alone, deprived of the
companionship he had enjoyed with the older man for the past two or
three decades. One of Bertolla's nephews continued to work in the master
clockmaker's workshop, but there did not appear to be any association
between the younger man and Father Borghesi.

At last, in 1794, Father Borghesi lost his sanity completely, and he was
forced to relinquish his pastoral duties to a curate. For the remaining
eight years of his life, he continued to live in the rectory of the
little parish church in Mechel where most of his life had been spent,
his needs undoubtedly attended by the parishioners he could no longer
serve. During this period, until his death at the age of 79 on June 12,
1802, Father Borghesi lived on, oblivious of those around him.
Seemingly, he retired to another world; perhaps to that universe which
he had tried to reproduce in his second clock.

The Clocks of Bartolomeo Antonio Bertolla

The ingenuity displayed in the Borghesi clock by its constructor,
Bartolomeo Antonio Bertolla, requires a consideration of the other
examples of his work that have survived. The most important of his
clocks are probably the one in the Episcopal Palace at Trent and another
made for the Baron of Cles.

The one which survives in the Episcopal Palace to the present time, is
extremely tall and is housed in an elaborately decorated narrow case of
black or ebonized wood approximately 9 to 10 feet in height. The upper
part of the case is decorated with elaborately carved and gilt rococo
motifs. The movement operates for one year at a winding, indicates and
strikes the hours, and shows the lunar phases. It has an alarm, and will
repeat the strike at will, indicating the number of the past hour and
the quarters. The gilt brass dial is decorated with silver-foliated
scrollwork in relief at the corners, inside the chapter ring, and within
the broken arch. Featured above the chapter ring is the coat of arms,
executed in silver, of the patron for whom the clock was made,
Cristoforo Sizzo di Noris. Di Noris was Bishop of Trent for 13 years,
from 1763 to 1776.

The clock which Bertolla made for the Baron of Cles is a tall, narrow,
case clock of ebony or ebonized pearwood which is approximately 9-1/2
feet in height. The decoration of the case is considerably more
conservative than the one made for Di Noris, but the black wood is
decorated with silver trim and carved designs in the wood itself. The
dial is decorated with silver scrollwork and spandrels within and around
a raised chapter ring. The clock operates for one month at each winding,
has an alarm, indicates and strikes the hours, and will repeat the
quarters. This handsome timepiece is still in the possession of the
descendants of the Baron of Cles.

[Illustration: Figure 21.--TALL-CASE CLOCK BY BERTOLLA in the Episcopal
Palace in Trent, made for Bishop Cristoforo Sizzo di Noris. A striking
and repeating clock with lunar phases. (_Courtesy of Museo Nazionale
della Scienza e della Tecnica, Milan._)]

[Illustration: Figure 22.--INTERIOR OF BERTOLLA'S WORKSHOP, showing
detail of ceiling. (_Courtesy Museo Nazionale della Scienza e della
Tecnica, Milan._)]

[Illustration: Figure 23.--INTERIOR OF BERTOLLA'S WORKSHOP, showing the
main workbench and the collection of clockmakers' tools. (_Courtesy of
Museo Nazionale della Scienza e della Tecnica, Milan._)]

[Illustration: Figure 24.--FUSEE CUTTER used by Bertolla. Now in the
collection of the Museo Nazionale della Scienza e della Tecnica,

[Illustration: Figure 25.--INTERIOR OF BERTOLLA'S WORKSHOP, showing
details of paneling and floor case with Bertolla manuscripts. (_Courtesy
of Museo Nazionale della Scienza e della Tecnica, Milan._)]

According to Pippa,[19] certain characteristics become apparent in a
study of the surviving clocks by Bertolla. The tall-case clocks are
narrow and range in height from 7-3/4 feet to 10-1/2 feet. The cases had
this excessive height in order to obtain the greatest fall for the month
and year movements which Bertolla constructed. For the weight assembly,
he substituted a drum wound with a key at the point of the driving wheel
in place of the customary pulley. The addition of an intermediate wheel
augmented the drop of the weight.

Bertolla's movements were solidly constructed from well-hammered brass
and iron. He favored the recoil anchor escapement in his clocks and the
Graham dead-beat anchor escapement with a seconds' pendulum. The
escapement was not always placed in the traditional location in the
upper center between the plates. Bertolla occasionally displaced the
pendulum to one side, to the lower part of the movement or placed it
entirely between two other small plates.[20]

He utilized every type of striking work, including the music-box
cylinder common in the clocks of the Black Forest and the rack and
snail. Bertolla most frequently employed the hour strike and _grand
sonnerie_. He often used a single hammer on two bells of different sound
with the rack and snail. An example of this type is the clock he
produced at the age of 80. To achieve the necessary axis of rotation for
the hammer, which is perpendicular to the plate when it strikes the
hours, it moves to an oblique position and displaces one of the two long
pins in an elongated opening.

Bertolla's dial plates were generally well executed, with a raised or
separate chapter ring applied to a brass or copper plate, such as a
copper-plate _repoussé_ and gilt with baroque motifs, or upon a smooth
brass plate with spandrels of _repoussé_ work usually of silver, in
relief and attached. The engraving of the chapter rings was excellent.
The hands were well executed in steel or perforated bronze, and
occasionally of _repoussé_ copper; gilt was applied to the hands made of
forged steel.

[Illustration: Figure 26.--DIAL PLATE of a brass lantern clock made by
Bertolla, found in his workshop after his death. (_Courtesy of Museo
Nazionale della Scienza e della Tecnica, Milan._)]

In the course of time, Bertolla's home workshop passed from one
generation to another within the family. Inevitably, it underwent many
modifications until the only original part of the building that remained
intact from Bertolla's time was his clockshop.

[Illustration: Figure 27.--MOVEMENT of a brass lantern clock made by
Bertolla. (_Courtesy of Museo Nazionale della Scienza e della Tecnica,

Within the last few years, the workshop room was acquired complete with
contents from Bertolla's descendants, and installed in the Museo
Nazionale della Scienza e della Tecnica in Milan as an exhibit of a
typical 18th-century clockmaker's shop. The original workshop was
dismantled in Mocenigo di Rumo and completely rebuilt in the museum,
including the walls, ceiling and floor. The paneling and woodwork of the
walls and ceiling, which have been preserved intact, are hand-cut fir,
with columns, trim and moldings carved by hand. A small painting is
featured in the center of the coffered ceiling. The original shop
benches and chests of drawers are set around the reconstructed shop and
Bertolla's tools and equipment laid out as they had been originally.
Other clockmaker's tools and equipment in the museum's collection are
also displayed. Approximately 40 percent of the tools are the original
items from Bertolla's shop. Parts of clocks and works in progress are
on view on the benches as they were in Bertolla's time.[21] Also
preserved in the museum are sketches found in Bertolla's manuscripts,
some of which are reproduced on the following pages.

[Illustration: Figure 28.--DETAIL OF WALL of Bertolla's workshop, with
regulatory clock made by his nephew, Alessandro Bertolla of Venice. Note
wheel layouts, etc., scribed in the paneling. (_Courtesy of Museo
Nazionale della Scienza e della Tecnica, Milan._)]

[Illustration: Figure 29.--TABLE CLOCK BY BERTOLLA in the collection of
Doctor Vittorio dal Lago of Bergamo. The dial indicates the days of the
week and of the month, the names of the months and lunar phases. The
clock strikes the hours and quarters and repeats. (_Courtesy of Sig.
Luigi Pippa of Milan._)]

The shop contains two completed clocks made by Bertolla. One is a
weight-driven lantern clock typical of the 18th century, Italian style
with brass dial, plates and posts, anchor escapement, and striking
work. The dial is engraved in the usual style of Bertolla's baroque
design, and the hands are of pierced bronze. Another clock associated
with Bertolla and found in the shop, was made by his nephew, Alessandro
Bertolla, who worked in Venice after his apprenticeship with his uncle
had been completed. This clock is a regulator with a seconds' pendulum
and sweep hand on an enameled dial. The original case has not survived.

[Illustration: Figure 30.--LAYOUT OF THE WHEELWORK of a clock made by
Bertolla for His Excellency Paulo Dona, inscribed "Design No. 1."
(_Courtesy of Museo Nazionale della Scienza e della Tecnica, Milan._)]

[Illustration: Figure 31.--PENDULUM ARRANGEMENT SKETCH for an
unidentified clock found in Bertolla's workshop. (_Courtesy of Museo
Nazionale della Scienza e della Tecnica, Milan._)]

[Illustration: Figure 32.--STRIKING CLOCK SKETCH found in Bertolla's
manuscripts. (_Courtesy of Museo Nazionale della Scienza e della
Tecnica, Milan._)]

[Illustration: Figure 33.--FIFTEEN-DAY STRIKING CLOCK SKETCH, inscribed
"Design No. 3," found in Bertolla's workshop. (_Courtesy of Museo
Nazionale della Scienza e della Tecnica, Milan._)]

[Illustration: Figure 34.--DIAL PLATE of a brass lantern clock made by
Bertolla at the age of 80. (_Courtesy of Museo Nazionale della Scienza e
della Tecnica, Milan._)]

[Illustration: Figure 35.--MOVEMENT of brass lantern clock produced by
Bertolla at the age of 80, showing details of movement and double bell.
(_Courtesy of Museo Nazionale della Scienza e della Tecnica, Milan._)]

One of the most interesting of Bertolla's clocks, and probably the last
one which he produced, was found in his workshop. This timepiece
indicates the hours, minutes and quarters by means of a single hand or
index. The weight-driven clock strikes the hours and quarters on two
bells with a single hammer. The chapter ring, which is soldered to the
dial plate, is marked for the minutes on the outer rim and for the four
quarters inside it. Over the center of it, is a semicircular opening in
the dial plate through which is visible a revolving disk attached behind
the dial plate. This disk is marked with the hours and revolves from
right to left, the current hour being indicated by a projection from the
minute ring. The brass dial plate is engraved with simple floral
designs in the corners and around the broken arch. There is no
comparison between this crude and simple decoration and the extremely
fine quality of the engraving on the dial plate of the Borghesi clock,
for instance. In the center of the dial plate is engraved the following:

     "Questo orologio l'ideai e lo feci nella mia avanzata età
     d'anni 80. Bart^{o} Ant^{o} Bertolla"

     (I designed and made this clock at my advanced age of 80 years.
     Bartolomeo Antonio Bertolla.)


[1] BORGHESI, _Novissimum Theorico-Practicum Astronomicum Authoma Juxta
Pariter Novissimum Mundi Systema..._, pp. 8-9.

[2] WENHAM, "Tall Case Clocks," p. 33.

[3] VON BERTELE, "The Development of Equation Clocks," parts 1 through

[4] ENGELMANN, _Philipp Matthäus Hahn_; VISCHER, _Beschreibung
mechanischer Kunstwerke..._.

[5] LLOYD, _Some Outstanding Clocks Over Seven Hundred Years,
1250-1950_, pp. 116, 118, 120.

[6] SAN CAJETANO, _Praktische Anleitung für Künstler..._.

[7] FRANCH, _La Valle di Non_.

[8] BONOMI, _Naturalisti, Medici e Tecnici Trentini_, p. 16

[9] AMBROSI, _Scrittori ed Artisti Trentini_, pp. 132, 525.

[10] Ibid.

[11] PIPPA, "Antonio Bartolomeo Bertolla," pp. 22-23.

[12] Ibid., p. 22.

[13] Ibid., p. 23.

[14] The abbreviation in the inscription "pLan" is difficult to
interpret. According to Father F. X. Winters, S.J., it may represent
"sit planetis" or "sit planetarum." The use of an abbreviation was
necessary to prevent the addition of another letter I or M, which would
have disturbed the formation of the chronogram desired. Literally, "sit
planetis" means "May he be eternal ruler _by_ [or _through_] favor of
the planets," while "sit planetarum" is to be translated "May he be
eternal ruler _of_ the planets." Father Winters considered both versions
somewhat overexaggerated and proposed that the best translation might be
"Long Live Francis I, Emperor."

[15] The word "Tempe" refers to the Vale of Tempe, in Thessaly, through
which the Peneus River flows. It is between Mounts Olympus and Ossa, and
is situated between the town of Larissa and the sea. In mythology, it is
told that these mounts were originally joined and Hercules separated
them to allow the river to pass between them. The word "Tempe" is also
used to mean any pleasant place. Thus, the inscription "Tempe
indesinenter clausa, Scaturigo signata" is literally translated "Tempe
always closed, A fount of water sealed up" or, freely translated, as "A
garden enclosed, a fountain sealed up."

[16] "Phoebi" or Phoebus, called Apollo, the sun god; Phoebes or Diana,
the moon goddess, sister of Apollo.

[17] PIPPA, op. cit. (footnote 11), pp. 23-25.

[18] PERINI, _Statistica del Trentino, Biblioteca Communale del
Trentino_, vol. 2, p. 57 (cons. 6, carta 9); TOVAZZI, _Biblioteca
Tirolese_, pp. 406-407.

[19] PIPPA, op. cit. (footnote 11), pp. 24-25.

[20] PIAMONTE, _La Nauna Descritta al Viaggiattore_.

[21] ESPOSTI, "La Sala 'Innocente Binda' al Museo della Scienza e della
Tecnica di Milano," pp. 18-21.



     [Translated from the section entitled "Synopsis Totius Operis
     Mechanici" in Francesco Borghesi's first book _Novissima Ac
     Perpetua Astronomica Ephemeris Authomatica


Of three movable indices, the farthest from the center of the dial is
fitted with an index on either side and marked with four segments of a
circle. Immediately below are five numbers, divided into the days of
setting the measure of the mean-synodic age of the moon, and into signs,
degrees of the signs, and of the distance of the moon from the sun.
These, in each revolution, revolve once around the solar disk
superimposed on the mean synodic-lunar disk, and also around the lunar
disk. The upper indices, meanwhile, in the two external greatest orbits,
measure the time continuously, in the accustomed manner of the
Germans--the middle index measuring by hours and the uppermost by the
first minutes [of hours].


Inside these three circles, perpendicular above their center, is a small
index of the seconds of minutes. At each first minute of time, being the
fastest of all, it describes the smallest orbit. Next to this are two
other slightly larger circles divided into 30 degrees, one [rotating?]
from the right, the other from the left. These two indices are arranged
in such a fashion that the one rotating from the observer's left
completes its period 12 times during one, mean, solar-astronomical year.
The one [rotating] from the right likewise completes its cycle 12 times
during the period of one mean-synodic moon. In between these, there is
placed another small sphere, divided into 40 arbitrary parts, whose dial
does not move automatically, but is moved by hand for speeding up or
slowing down the course of the time, or of the perpendicular.


Diagonally from the sides of the center of the three larger indices, six
other indices revolve: three on the left from one center, and three on
the right from another. The uppermost of the three which are on the
right of the observer [and which are] decorated with a small disk of the
sun, runs its cycle once during a mean solar-astronomical year. The
second measures the distance of the sun from its apogee. The third
revolves 12 times, with each lunar revolution from one node to the same
[repeated] node. Under the point of the uppermost index, first lie the
months of the year which are inscribed, and the days of each month, but
having only 28 days assigned to February; then the signs of the zodiac,
and their several degrees. The circle corresponding to the middle index,
extending through the first semicircle from apogee to the lower perigee
and returning through the second semicircle to the upper locations of
apogee, shows the true equation or eccentricity of the sun, joined with
the little equation of the moon in syzygy. [These equations are]
measured by geometric-astronomic proportion for each distance of the
sun from its apogee or perigee in degrees, and in sufficiently small
parts of degrees, with the title added above in their proper places,
whether an addition is to be made to the mean location of the sun or a
subtraction from the same, so that the true longitude of the sun may be
calculated. Three circles are assigned to the lowest index, of which 30
degrees of distance of the moon from its nodes comprise the larger. The
middle circle is based on the hypothesis of the mean invariable
diameters (that is, of the sun, the moon, and the terrestrial shadow),
and is divided into hours and quarters of duration. The last circle is
divided by the trigonometric laws into the inches of magnitude of lunar
eclipses. Lying between these circles, there is another eccentric circle
(black with a spot) exhibiting the shadow of the earth, in which the
little moon sinks itself, carried by the lowest index. In any ecliptic
full moons, the patent number of inches of immersion somehow affects the
minds of the cultured, but also the scheme of maximum obscuration
affects the eyes of the illiterate themselves.


Of the three indices which revolve from the left, the uppermost
completes its cycle within 12 hours, just as the hour index. The middle
one with two pointers on diametrically opposite sides, carries the marks
of conjunction and opposition of the luminous bodies, with a movement
equal to the course of the sun from lunar apogee or perigee. The lowest
index, fitted with a single pointer, indicates the motion of the moon
from its apogee or perigee. Under these three indices, there is situated
a common circle, divided into 12 parts, each of which are further
divided into 30 parts through its outer circumference. I have said a
common circle, for, with respect to the first index, the division
represents 12 hours, and the double subdivision representing the double
set of minutes of the hours serves for an excitator for anytime at all,
at will. For as often as the little index reaches the twelfth hour,
first being moved by hand wherever you prefer, a little hammer strikes
the little bell many times. But if you observe the second or the third
index, the first division provides the signs, and the subdivision of the
signs gives the individual degrees of the distance of the sun from the
lunar apogee, or of the moon from its apogee, respectively. To this is
added two other interior circles from the same center: to the larger is
inserted the equation of the center of the moon in its conjunctions and
oppositions; and on the smaller the equation of the same moon in its
quarters, astronomically-geometrically proportioned to the distance of
the moon from its apogee or perigee. In the first case, the equation is
to be subtracted from the mean longitude of the moon, descending from
apogee to perigee; in the second case, to be added to the mean longitude
of the moon ascending from perigee to apogee; and, in the third
semicircle of the index, as the rubric directs, common to both
equations, added around the center.


Perpendicularly under the center of the machine, two other indices are
carried about one and the same center. The one nearer to the
observer--bearing in one of two points diametrically opposite the small
disk of the sun, in the other the disk of the moon--runs a course equal
to the motion of the sun from the head or the tail of the dragon
(_Draco_). The other, of simple construction, marked with a small moon,
signifies in like manner the motion of the moon from the head or the
tail of the dragon.

Immediately below, there is a larger circle, common [referring] to both
these indices, which is divided into 12 parts. Each of these parts in
turn, in the outer periphery, is subdivided further into 30 parts, which
are the 12 signs of the zodiac and the individual degrees of the signs
of distance of the sun and the moon from the head of the dragon.

In the second circle is read the latitude of the moon, measured by
degrees, etc., on a trigonometric scale, by signs and degrees of
distance of the moon from its nodes, that is, from the head or tail of
the dragon. When the second index is descending from the head of the
dragon to the tail, the latitude will be to the north of the solar path;
that is, the ecliptic. On the other hand, it will be south of the
ecliptic when the same index is returning upward from the tail to the
head of the dragon as advised by the title inscribed on the third

Finally, on the fourth and last circle are seen more prime minutes of
the circle for reducing the orbit of the moon to the ecliptic. That the
true longitude of the moon may be obtained more accurately, these must
be subtracted from the longitude of the moon already calculated in the
first and third quadrant of the circle of the second index. On the other
hand, they are to be added to the same in the second and fourth
quadrant, as is noted in their respective places, according to the
theory of right ascensions.

Here, then, [you have] as finally completed, delineation of the great
index which was partially described before in this book.

From two points of that index which perpendicularly correspond to the
center of these circles, a pair of compasses, by an unvaried aperture up
to the circumference of the first larger circle, has marked off four
segments of a circle. The two larger segments, equal among themselves,
in one aperture refer to the sun, and the two smaller in the other,
likewise equal, refer to the moon. The one pointer is for determining
the solar eclipses; the other, for lunar. Both segments of each
division, like little wings of the index, stretch to the extent of the
degree of distance of the moon from its nodes, and to which that
determined latitude corresponds. On one side, that latitude precisely
equals the radii of the earth, the sun, and the moon, as the termini of
solar eclipses; and, on the other side, precisely equals the radii of
the earth's shadow and of the moon, as the confines of lunar eclipses.
The apexes of the last index, diametrically limited [opposite], indicate
the age of the moon, and its mean distance from the sun; one pointer,
upon which the sun sits, measuring the mean days and degrees from the
full moon; the other, on which the moon sits, measuring the mean days
and degrees from the new moon.


Besides the larger and smaller indices already mentioned, all [of which]
revolve within the periphery of the three largest circles, six dials in
this clock also revolve within the same circles which are to be seen
through six openings of the frontispiece. The first of these, intended
to indicate the phases of the moon by an unusual method (completely
black, and decorated with the characters of the principal aspects of the
moon) continually revolves interiorly around the center of the machine
and at the new moon, it completely removes from sight the face of the
moon through the round window. It continually recedes through the first
half of the circle until, at the time of the full moon, it restores the
moon, looking out with a full star. Soon again, too slow to be
observed, it returns through the other half of the circle, so that in
the next conjunction, the whole face of the moon may have a covering of
darkness, once again to be removed.

The other dials are moved by spontaneous advances at stated times. The
first of these shows, through a square opening, the day of the month;
the second, through another opening, shows the current day of the week
with the characters of the seven planets which, according to ancient
superstition, preside over each day of the week (now, by a truer form of
religion divided by the Church into ferias, etc.); that is, the sun, the
moon, Mars, Mercury, Jupiter, Venus and Saturn, to which I have added
the numbers of the ferias. These two little dials are advanced daily, by
a sudden movement at midnight. The remaining three are changed
automatically only once a year on the first of January.

The first of these dials contains five little cells, opening from a
common window: in the first cell, at the edge of the dial, is found the
dominical letter; in the second, the cycle of the sun; in the third, the
character; in the fourth, the sign; and, in the fifth, the house of the
planet dominating the year. The second dial shows the epacts, with the
golden number. The third, and last of all, shows the Roman cycle.

Finally, as indicated by the epact and the dominical letter in an
immovable table added outside, are the feastdays and other movable
events of the year; that is, Easter, the four seasons, the Rogation
Days, etc.


But lest the various movements of the indices and the various beginnings
of the divisions tend to cause some fatigue, the precaution has been
taken, that all the indices by common law are moved from the top towards
the right of the observer, and from thence all the arithmetic divisions
of the circles take their beginning. And lest the multitude of different
figures should deceive the eye, the larger divisions of the circles have
been marked by Roman numbers, that is, by capital letters of the
alphabet; others, in other places, by differently colored numbers. Thus,
the movements of the indices, the distribution of the circles and the
multitude of numbers not only do not disturb the eyes and the mind, but
rather marvelously delight them.


After having completed briefly the description of the dial and the
indices and their motions, I have not without reason delayed in
satisfying the desires of many who wish to learn at least the method by
which, from this mechanism, may be calculated the true times of new and
full moons, and their ecliptics. In order to make these matters clearer,
it is necessary that they be explained here at greater length.

With the indices, then, adjusted astronomically-geographically to the
longitude of any given region, and to the mean time whether past,
present or future, and assuming the clock to be in normal operation (as
at present it has been for a whole year and more), then the moon will be
in conjunction with the sun in the heavens. When the equations on the
mechanism are examined, the sun and moon shall be found to be in the
same degree of longitude, and in the same part of a degree. There will
also be an ecliptic new moon that is in conjunction with a solar
eclipse, or rather with a terrestrial eclipse. This will occur if, at
that time, both apexes of the first index, located below the center of
the clock, are hidden by the two segments of the circle extending from
the center of the mechanism through the lowest index.

And the eclipse will be greater and greater and, consequently, visible
in more regions of the earth, the more deeply the two pointers,
indicating the distance of the sun from its apogee, are hidden in the
center of the segments.

But whether the eclipse takes place in the head or in the tail of the
dragon, or whether it is north or south, is indicated by the small disk
of the sun attached to one of the two pointers hidden by the segments of
the circle. If, at that time, the little disk shall be found in the head
of the dragon inscribed on the plane of the dial, then the sun has been
snatched from the earth and ingloriously entombed, as it were, in the
huge jaw of the dragon. Then, ... the heavens themselves will lend aid
to the woeful pomp of the senseless funeral in full darkness by suddenly
lighting the unhappy lamps of the fixed stars. However, if the little
disk occupies the tail of the dragon on the mechanism, then the sun in
the heavens also, as if freed from the toils of the immense dragon's
tail, will emerge without difficulty.

The center of the eclipse will traverse the hemisphere of the earth
north of the solar path, always nearer to the pole of the ecliptic, in
proportion to the inclination of the disk to the north. On the other
hand, if the little disk inclines to the left semicircle, then the
people south of the solar path will enjoy the spectacle of the total
central eclipse.

But if the little disk remains neutral (inclining neither way) and
remains halfway between the two sections of the circle, then the
greatest solar eclipse will take place at the equator and those who live
near the poles of the ecliptic will not enjoy a trace of that eclipse.
This is because the half of the equatorial diameter enormously
outmeasures even the greatest apparent semidiameters of the sun and of
the moon, even taking as a norm the smallest horizontal parallax of the

What has been said about the true new moon is to be understood also,
proportionately, about the true full moon. For when, with respect to the
equations of the centers, the moon shall be distant on the mechanism by
a full semicircle from the sun (also in the heavens it will be truly in
opposition to the sun) there will be a true full moon. Likewise, the
moon in the heavens will be in eclipse if, at the time of opposition,
the pointers of the little index (which we mentioned before) situated
below the center of the clock are so far away from the belly of the
dragon that they are forced to lie under the two smaller segments of the
circle which, in all full moons, are always to be moved from the index
of the synodic moon to the region of that little index. As a matter of
fact, the closer the little pointers approach to the middle of the
segments, the more obscured it will be.

You will know, furthermore, that the eclipse of the moon occurs in the
head of the dragon if the disk of the little moon, attached to the other
point of the little index, is raised to the head of the dragon;
conversely, when the little disk of the moon inclines to the tail, the
eclipse is taking place in the tail of the dragon.

And, accordingly, when you observe the little moon of the index inclined
to one or other section of the circle, so also in the heavens, the
eclipse of the moon is only partial and the northern or the southern
part of the moon is illuminated.

The current time will indicate whether the lunar eclipse is visible or
not. As the new moon ecliptic falls during the day, the eclipse will not
be visible, since the earth denies a sight of the moon which is below
the horizon. But, conversely, if there are no clouds, the eclipse will
be visible anywhere, if the luminous bodies are ecliptically in
opposition at night.

Since lunar eclipses appear to all people as being of the same magnitude
and duration, and begin and dissipate at the same absolute moment of
time, I decided to reveal another facet of this spectacle on the right
side of the center of the clock (see chapter III above). There, at the
time of the true ecliptic full moon, as the pointer of the third little
index shows, you can ascertain the hours, etc., of duration, and the
inches of greatest obscuration. The little moon attached to the index is
a model of the actual eclipsed moon.


Thus, with the aid of this machine, solar and lunar eclipses of the past
can be recalled and future ones can be foreseen. Indeed, if the index of
prime minutes is speeded up by hand, whose wheel imparts motion to the
other indices and shields, then, the dials and openings will foretell
the year, month, day, hour, etc., of any future eclipse. I foresaw that
the times would thus be evolved too slowly, and that the clock wheels
would be considerably worn by repeated experiments (if, for instance, by
the rotation of the index of prime minutes, to whose period only a
single hour corresponds, the future new and full moon ecliptics were
being investigated). Therefore, I took care that the wheel which
immediately communicates motion to the index of the synodic moon should
be so fitted internally to the mechanism that by the reversal of any
external index, the wheel would be removed from its proper position;
whenever desired, it could be quickly and most accurately restored to
its proper place.

In this way, since the close meshing of the wheels is released, you can
extend the experiment for many years, even for many centuries. You have
only to guide with your hand the index of the synodic moon on the
circles, always intently observing whether, in the passage which this
index makes over the little index, both pointers of the little index are
hidden by the segments of the circle. Having observed this, look at the
index moved by hand, for if this has carried the solar disk halfway
between the two larger segments of the circle to the region of the
hidden little index, then you will know that eclipse will be a solar
eclipse. On the other hand, you will know that it will be a lunar
eclipse, if the index (moved by hand) has carried the moon, situated
between the two smaller segments of the circle, to the same region
(i.e., the hidden part of the circle). The solar disk and the lunar disk
alternately will reveal to you the circumstances of both eclipses. The
current year will be given by the Julian period, reducible to any
desired epoch, and, contained in the solar cycle, the golden number and
the Roman cycle. The month of the year and also the day of the month
will be indicated by the pointer of the little index, first on the right
side of the clock. And what I have said of future eclipses should be
equally understood of past eclipses, so long as the index, which can be
moved either way at will, is moved in reverse.

Finally, though 55 wheels were employed to carry so many dials, all are
driven by one source of power not exceeding the third part of a Germanic
hundred-weight which, suspended at the geometric height of five feet
(about the ordinary stature of a man), keeps the whole machine in
operation for a hundred days and more.

Although the machine repeats hours and quarter hours at will and,
consequently, the number of wheels and the rest of the apparatus
necessary for these functions is thereby increased, it has not grown to
an unwieldy size, however much one might erroneously imagine it to be.
It does not exceed the bulk of ordinary clocks hanging from a wall;
indeed, it scarcely equals these.

The entire machine, ready for operation, does not weigh more than 156
ounces, although it is made of steel or brass throughout and further
weighted with two bells and a rather large brass dial-plate.

Of course, there are many more things to be said, especially about the
mechanical structure of the wheels, but fearing to tire my kind reader
unduly by exceeding the bounds of a summary, I am forced to put an end,
though unwillingly, to this sufficiently shortened explanation of the
work. I have hope of giving satisfaction to many more when I shall have
communicated to the learned world another and completely new automatic
work, grander than this present one. It is already theoretically
completed in all its calculations, but still to be worked out
mechanically from the very beginning, if but God, thrice Best and
Greatest, bless the undertaking and mercifully grant life and health--to
whom be in, and from, and through all things, all honor and glory in
eternity and beyond.


The following works have been used in compiling the material for this
paper. They are frequently referred to in the text in shortened form.

     AMBROSI, FRANCESCO. _Scrittori ed artisti Trentini._ Trent:
     Giovanni Zippel, 1883.

     BONOMI, L. _Naturalisti, medici e tecnici Trentini._ Trent:
     privately printed, 1930.

     BORGHESI, FRANCESCO. _Novissima ac Perpetua Astronomica
     Ephemeris Authomatica Theorico-Practica._ Trent: Giovanni
     Battista Monauni, 1763(?).

     ---- _Novissimum Theorico-Practicum Astronomicum Authoma Juxta
     Pariter Novissimum Mundi Systema._ Trent: Giovanni Battista
     Monauni, 1764.

     ENGELMANN, MAX. Philipp Matthäus Hahn. Berlin: Verlag Fischer,

     ESPOSTI, ALFREDO DEGLI. La sala 'Innocente Binda' al Museo
     della Scienza e della Tecnica di Milano. _La Clessidra_ (July
     1960), anno 16, no. 7, pp. 18-21.

     FRANCH, LEONE. _La Valle di Non._ Trent, 1953.

     LLOYD, H. ALAN. _Some outstanding clocks over seven hundred
     years, 1250-1950._ London: Leonard Hill, 1958.

     MOSNA, EZIO. _Trento._ Trent, 1914.

     PERINI, AGOSTINO (compilatore). _Statistica del Trentino,
     Biblioteca Communale del Trentino._ Vol. 2, p. 57 (cons. 6,
     carta 9).

     PIAMONTE, GUISEPPE. _La nauna descritta al viaggiattore._
     Milan, 1829.

     PIPPA, LUIGI. Antonio Bartolomeo Bertolla. _La Clessidra_
     (January 1961), anno 17, no. 1, pp. 22-25.

     SAN CAJETANO, DAVID À. _Praktische Anleitung für Künstler, alle
     astronomische Perioden durch brauchbare bisher noch nie
     gesehene ganz neue Räderwerke mit Leichtigkeit vom Himmel
     unabweichlich genau auszuführen, sammt Erweiterung der Theorie
     des neuen Rädergebäudes._ Vienna: privately printed, 1793.

     TOVAZZI, GIANGRISOSTOMO. _Biblioteca Tirolese._ Vol. 2, art.
     329, MS. 168, pp. 406-407. Trent, 1780.

     VISCHER, GEORGE F. _Beschreibung mechanischer Kunstwerke,
     welche unter der Direktion und Anweisung M. Philipp Matth.
     Hahn, Pfarrers in Kornwestheim..._. Stuttgart: Mezler, 1774.

     VON BERTELE, HANS. The development of equation clocks. _La
     Suisse Horologere_ (1959-1961), parts 1 through 5.

     WENHAM, EDWARD. Tall case clocks. _The Antiquarian Magazine_
     (May 1927), vol. 8, no. 4, p. 33. [The Borghesi clock is
     illustrated only from a photograph of the Anderson Art
     Galleries in New York, and mislabeled "Astronomical Clock made
     in Jena, 1656, in elaborate mahogany case."]

       *       *       *       *       *


For sale by the Superintendent of Documents, U.S. Government Printing
Office Washington, D.C. 20402--Price 70 cents


Aristarchus of Samos, 54

Bertolla, Alessandro, 65

Bertolla, Bartolomeo Antonio, 31, 34, 36, 47, 51, 52, 57, 62, 63

Borghesi, Father Francesco, 31, 70, 71

Brahe, Tycho, 54

Butzjäger, Johann Georg, 36, 37

Charles VI, Emperor of Austria, 32

Cles, Baron of, 57, 59

Copernicus, 54

Di Noris, Cristoforo Sizzo, 59

Evelyn, John, 32

Francis I, Emperor of the Holy Roman Empire, 42, 44, 52, 58

Hahn, Father Philipp Matthäus, 33

Klein, Father ----, 33

Lippi, Fra Lippo, 42

Longomontanus, Christian Severin, 54

Maria Theresa, Empress of Austria, 31, 41, 42, 44, 57, 58

Meton, 48

Monauni, Giovanni Battista, 40, 52

Philolaus, 54

Ptolemy, 54

Pythagoras, 54

Quare, Daniel, 32

Riciolus, 54

San Cajetano, Brother David à, 33

San Daniele, Father Aurelianus à, 33

Sully, Henry, 32

Tompion, Thomas, 32

Tovazzi, Giangrisostomo, 57, 58

Williamson, Dowe, 32

Williamson, Joseph, 32

Winters, Father S. X., S.J., 42

Winz, Johann Christian, 36, 37

Wisshofer, Peter, 36, 37

       *       *       *       *       *

Transcriber's note:

Footnotes have been moved to the end of the main section of the paper,
and illustrations have been moved to eliminate breaks in paragraphs. Two
'side bar' sections set off from the main text in the original are
indicated by lines of asterisks before and after the side bar. Minor
punctuation errors have been corrected without note. The following
typographical errors have been corrected:

    p. 37  ... his curiosity increased ... [Had 'curiousity'.]
    p. 41  Bertolla apparently wavered in ...  [Had 'waivered'.]
    p. 43  ... contained within asterisks, carries ... [Had 'carrie'.]
    p. 45  ... Assidvo proni donant di cvncta labori. [Had 'ronip'.]
    p. 45  ... assiduous laborer.) The same ... [Had 'saem'.]
    p. 48  ... 12 signs of the anomaly, within ... [Had 'anamoly'.]
    p. 51  ... the larger size of uppercase letters ... [Had 'letter'.]
    p. 54  ... rightly conceive my new system of the ... [Had 'sytem'.]
    p. 55  ... leading point of the system ... [Had 'they'.]
    p. 55  ... Cancer; Austral [the southern] ... [Closing bracket added.]
    p. 55  ... of the earth are always held in one ... [Had 'alway'.]
    p. 56  ... all things in their circles so that ... [Had 'than'.]
    p. 56  ... satellites, etc., eccentrically ... [Had 'excentrically'.]
    Footnote 4: _Philipp Matthäus Hahn_ [Had 'Matthaus'.]

*** End of this Doctrine Publishing Corporation Digital Book "The Borghesi Astronomical Clock in the Museum of History and Technology - Contributions from the Museum of History and Technology, Paper 35, the Smithsonian Institution United States National Museum Bulletin 240" ***

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