Academic journal article Transactions of the American Philosophical Society

A Twin Legacy: Hyperbolic Lenses and Mechanical Makers

Academic journal article Transactions of the American Philosophical Society

A Twin Legacy: Hyperbolic Lenses and Mechanical Makers

Article excerpt

IN THE WAKE OF PUBLICATION

The circulation of La Dioptrique introduced the educated and technical communities of Europe to the promise of the hyperbolic lens, as well as to the promise of machine-made lenses, and a number of savants and artisans took up the task of trying to make a hyperbolic lens, either by machine or by hand. Others began to experiment with a variety of mechanical devices and systems to aid in the making of spherical lenses. It is more difficult to discover the nature and progress of lens making projects taken up by artisans, because in the majority of cases they did not publish their results and often guarded their innovations and techniques as trade secrets. Published works after 1637, however, provide excellent evidence that natural philosophers and active astronomers were preoccupied by mechanical systems for the production of lenses for telescopes. As I have suggested, none of these systems succeeded in making lenses, either spherical or hyperbolic, that were comparable to the handcraft techniques of the master Italian lens makers and those who emulated them. The enduring promise of mechanized systems, in the absence of any concrete success, serves as a testimony to the power of the idea and the ideal of the machine in the elite circles of seventeenth-century science. Moreover, I believe the preoccupation with mechanical devices for lens making subtly betrays tensions in the emergent relationship between speculative natural philosophers and craftsmen, itself a result of collaborations on devices like telescopes, air pumps, and the other new instruments of scientific investigation. The project of displacing the artisan by building machines to ensure the excellence of lenses and telescopes (regardless of the manual skill of the craftsman) strongly suggests an impulse on the part of a number of natural philosophers to distinguish the instrument of scientific investigation from the traditions of practical instrument-devices from which it arose. By mechanizing the system for making the crucial components of optical instruments, natural philosophers were working to free their pursuit of truthseeking instruments from dependence on the vagaries of handcraft. Descartes' frustration with craftsmen by the end of his life went beyond disappointment with the limitations of their craft, to a bitterness reflected in his complaints to his correspondents about the extravagant sums that lens grinders garnered for their inadequate labor.1 Other natural philosophers delivered even more scathing assaults on the character and ability of the optical craftsman.

I turn now to accounts of several important mechanical lens making systems that received attention after the publication of La Dioptrique.

RHEITA

Anton Maria Schyrleus de Rheita, a Capuchin astronomer of Bohemia, brought forward in 1645 a quirky book of astronomy entitled Oculus Enoch et Eliae.2 Among the "useful and happy works" heralded by this text was an ingenious mechanical system for producing the new hyperbolic lenses.3 Despite an avowed anti-Copernicanism and a facility for interlacing scripture and astronomy, messianic visions and physical optics, Rheita was not at all peripheral to the community of astronomer-savants of Belgium and Holland, even if he was perhaps eccentric to it. The striking title of his major work reflected his faith that the new optical devices were prophetic instruments, engaged, like the ancient prophets Enoch and Elijah, in a life and death struggle with the devil himself. A student of Gutschoven, who had studied mathematics and optics with Descartes, Rheita went on to become the instructor of Johann Weisel, who would become one of the better-known lens makers outside of 1IaIy.4 Rheita himself is often credited with the discovery of the terrestrial telescope, made out of four convex lenses and featuring an erector lens to right the inverted image of an astronomical telescope,5 and Rheita's familiarity with the craft of lens making is demonstrated in his ciphered reference to a new technique for polishing spherical lenses using sheets of blotter paper treated with emery and shaped wet to fit the lens. …

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