The Borghesi Astronomical Clock in the Museum of History and Technology: Contributions from the Museum of History and Technology, Paper 35

In Short

This monograph examines the intricate history and technical mastery behind the astronomical clocks of Father Francesco Borghesi. Built in the mid-1700s, these elaborate timepieces served as both scientific instruments and symbolic representations of the divine order. The narrative follows the life of the clockmaker Bartolomeo Antonio Bertolla, who transformed Borghesi’s theoretical designs into reality. Through careful historical reconstruction and translation of original Latin texts, the work explores how these machines—designed to predict eclipses and planetary motions—survived the scrutiny of skeptics and the passage of time to enter the collections of history.

The Story

The narrative begins within the intellectual climate of 18th-century Austria, a period when astronomical clocks transitioned from simple timekeepers to grand "automata" capable of simulating the universe. Father Francesco Borghesi, a man of faith and science, finds himself frustrated by the inaccuracies of existing planetary calculations. He posits that if the laws of the heavens can be understood, they can also be replicated in brass and iron. Borghesi envisions a machine that does more than track the hours; he wants a device that displays lunar phases, solar eclipses, and the complex, shifting tides of the earth.

However, a vision is not a mechanism. Borghesi lacks the specialized skill to forge the gears and springs necessary for his ambitious design. He finds his collaborator in Bartolomeo Antonio Bertolla, a craftsman of the Tyrol whose disciplined apprenticeship under the clockmaker Johann Georg Butzjaeger provided him with the necessary expertise. Bertolla is a figure of quiet diligence. The record of his apprenticeship, preserved by his descendants, serves as a testament to the rigor of the guild system, confirming his transition from a promising student to a master capable of executing Borghesi’s complex, often nightmarish mathematical theories.

As the clock takes shape, it becomes a center of controversy. Borghesi publishes his findings in two small volumes, written in Latin, which serve as both user manuals and philosophical defenses of his work. He invites the reader to test his system, even acknowledging that his peers might dismiss his ideas as the "delirium of an unbridled imagination." Yet, he persists, integrating subtle mechanical adjustments to account for leap years, planetary anomalies, and even the "head and tail of the dragon"—the nodes where eclipses occur.

The physical construction of the clock is a marvel of precision. It incorporates elaborate dials featuring cherubs, engravings of Atlas, and complex chronograms that total the year 1764, the date of its completion. The clock is eventually presented to Empress Maria Theresa of Austria. Its journey into the Imperial Court sparks envy and skepticism from anonymous contemporaries who doubt its accuracy. Historians like Giangrisostomo Tovazzi later suggest that such criticism was born of professional jealousy, a reminder that genius often invites resistance. The clock survives this social turbulence, passing into history as an artifact that treats "a thousand years... as one day." The final chapters of the story move away from the clock’s creation to the preservation of its legacy, tracking how the workshop of Bertolla—a space where brass was hammered into celestial truth—slowly faded while the machines themselves remained as enduring witnesses to a time when humanity sought to bind the heavens to the dial.

How It Unfolds

The intellectual challenge Borghesi identifies the limitations of contemporary mechanical astronomy, arguing that human calculation is insufficient to represent the true complexity of celestial bodies. He posits that a perfect automaton could reconcile these movements for the human eye.

The artisan’s formation The narrative shifts to the early life of Bartolomeo Antonio Bertolla, whose three-year apprenticeship provides the foundation for his later precision work. This period establishes the technical rigor required to realize Borghesi’s theoretical designs.

The construction and defense Borghesi publishes his Latin treatises, inviting both study and ridicule while detailing the clock’s inner workings. He addresses the skeptics directly, demanding that they either prove his system false or accept its accuracy.

The imperial legacy The clock is completed and presented to the Austrian court, where it becomes a subject of both admiration and envy. The text examines the subsequent historical accounts of its reception, including the criticisms of anonymous mathematicians and the defense offered by later chroniclers.

The People

Father Francesco Borghesi is the intellectual heart of the work. Driven by a deep, almost obsessive need to "bind by laws" the artificial heavens, he moves from theoretical frustration to the creation of a machine that claims to map the cosmos. He is candid about his own difficulties, admitting that his writing is "meager and succinct" due to the overwhelming pressure of his work.

Bartolomeo Antonio Bertolla provides the steady, skilled hands required to bring Borghesi's vision into the physical world. A master of "great clocks," his diligence ensures that the complex gears and escapements actually function. He is the bridge between the abstraction of mathematics and the reality of metal.

Empress Maria Theresa stands as the recipient of the masterpiece, representing the patronage that sustained such grand scientific endeavors. While she remains a distant figure, her court serves as the ultimate proving ground for the clock’s value.

Giangrisostomo Tovazzi acts as the voice of historical defense, recording the clock’s survival and the inevitable presence of "envy" that follows great achievement. His account highlights the timeless nature of intellectual conflict, suggesting that even a clock that predicts the future cannot escape the petty resentments of the present.

In Its Own Voice

"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."

Borghesi describes the frustration of past clockmakers who failed to capture true celestial motion.

"So that, all exaggeration aside, a thousand years pass, in the sight of this clock, as one day!"

Borghesi emphasizes the immense temporal scale his machine is capable of navigating.

"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."

Borghesi invites his critics to engage with him while he is still alive, rather than waiting to mock his work after his death.

What It's Really About

The book is a study in the intersection of human ego and cosmic order. It probes the question of whether a mechanical device can truly represent the "Gordian knots" of the universe. Beyond the gears and pendulums, the work asks how much of our perception of time is natural and how much is an artificial construct we build to stave off the chaos of the infinite. It is a meditation on the burden of knowledge—the "hateful cares" that Borghesi claims kept him from explaining his work more fully—and the legacy left by those who attempt to compress the vast, untouchable movements of stars into the reach of a human hand.

Why Read It Today

Readers with a fascination for the history of science or the intricate mechanics of horology will find this a deeply rewarding, if specialized, read. The text does not shy away from the technical demands of the subject; it provides a granular, almost meditative look at the gearing, dials, and escapements of the Borghesi clock. What stays with you is the sheer audacity of the 18th-century mind—the belief that one could, with enough brass and prayer, make the clockwork of the universe visible in one’s own parlor.

The book is not without its difficulties. The prose reflects the academic tone of a mid-century museum bulletin, and the inclusion of lengthy, translated Latin prefaces and technical lists will test the patience of a casual reader. Furthermore, the 18th-century attitude toward mechanical religion and the "superstition" of planetary days provides a period-specific lens that requires some historical context to fully appreciate. However, for those who value the precision of craftsmanship and the persistence of human curiosity, the journey through the Borghesi workshop is a quiet, profound experience. You are left with the image of a machine—a "new world supported on new poles"—that continues to tick in the collective memory, long after the hands that crafted it have turned to dust.