The Artificial Teledioptric Eye, or Telescope, 1685–86

By Paula Findlen ~

Originally published in Hidden Treasure: The National Library of Medicine, 2011.

Installments of this lavishly illustrated encyclopedia of the anatomy, physiology, physics, mathematics, and instruments of sight—770 dense folio pages—began appearing in the city of Würzburg in northern Bavaria in 1685. Influential in its own time, the Artificial Teledioptric Eye (“Derived through a New and Lasting Method from Hidden Principles of Natural and Artificial Things, and Explained and Summarized from a Physical Foundation of a Threefold Nature, whether Mathematical-Optical, Mechanical, or Established through Practice”) continues to fascinate historians interested in the invention of the “magic lantern” and the uses of the camera obscura, in the era before the invention of photography and cinematography.

Its author, Johann Zahn (1631–1707), was a German canon in the austere Premonstratensian monastic order. He was also a disciple of the Jesuit Caspar Schott (1608–66) and, via Schott, the Jesuit polymath Athanasius Kircher (1602–80). When Schott returned to Würzburg in 1655 to teach mathematics and physics, he earned his reputation assisting Kircher, whose dazzling array of writings on virtually every aspect of human knowledge included the Ars magna lucis et umbrae (Great Art of Light and Shadow), published in 1646 but revised in 1671 to include an image of a magic lantern. This treatise, along with Schott’s works on curious technologies, inspired Zahn to produce his Artificial Eye.

Zahn crafted his publication to compete with the most lavish baroque encyclopedias of science, advertising it as a “curious theoretico-practical work embellished with a great variety of things” and including every new and useful art that a philosopher or practitioner of mathematics would want to know. Well-informed readers would have surmised his indebtedness to Kircher and Schott when reading his announcement that his book contained “many new, secret, and curious technasms”—a phrase that captures the phantasmagoric quality of their vision of technology—and his promise to bring the mysteries of the telescope “from shadow into light.”

In his preface Zahn celebrates the German tradition of optics and mechanical invention. He had a broad understanding of the history of instrument making in the previous century and was well informed about the most recent developments in astronomy, including the debates over the rings of Saturn, Isaac Newton’s invention of the reflecting telescope, and Danzig astronomer Johannes Hevelius’s workshop for grinding lenses for the telescopes perfected in his famous rooftop observatory. It is a state-of-the-art discussion of instruments of vision and their utility in the progress of scientific knowledge and, at the same time, a great example of baroque Hermeticism: Zahn coupled his technical account of vision and the enhancement of the senses with a joyous celebration of the metaphysical qualities of light as the origin of the cosmos and a reminder of God’s continued presence in the world.

Zahn’s baroque diagram of the anatomy of vision (left) needs to be viewed in relation to his creation of a mechanical eye (right), the scioptric ball designed to project the image of the sun in a camera obscura. National Library of Medicine #101596445

Zahn’s baroque diagram of the anatomy of vision (left) needs to be viewed in relation to his creation of a mechanical eye (right), the scioptric ball designed to project the image of the sun in a camera obscura. National Library of Medicine #101449185

Arguing that one cannot understand the “artificial eye” without an explanation of the “natural eye,” Zahn begins with a discussion of the anatomy and physiology of the eye. He draws on the work of theorists such as Johannes Kepler, anatomists such as Thomas Willis, and Kircher, who provided an explanation of light and color. Zahn then builds a “material eye”—an experimental model—as a prelude to his critical assessment of the different kinds of telescopes then available, and preliminary to his discussion of distorting (catoptrical) devices, binoculars, burning mirrors, and the camera obscura (which was used to view sunspots). He describes lens-grinding machines, the “English microscope” pioneered by Robert Hooke, and Newton’s telescope. The book concludes with an account of the first device capable of projecting an image with artificial light—the magic lantern—whose basic principles Zahn credited to Kircher while offering concrete examples of how to build and use a projector. A virtuoso of the lens, Zahn experimented with combinations of lenses, built machines to focus and project images with light, and fostered the spread of the magic lantern.

We remember Zahn today as the man who almost invented the camera, but he did far more than that. Consider his telescope mounted in a scioptric ball with a steering rod to track the sun’s movements and project its image into a darkened room. Zahn helps us to understand why the age of Kepler, Descartes, and Newton was also the era of the artificial eye. He allows us to envision this new age of instruments as an era of wonder, curiosities, and paradoxes animated in the shadows of his science.

Paula Findlen is Ubaldo Pierotti Professor of Italian History at Stanford University. Her publications, in addition to many essays on science and culture in the early modern world, include Possessing Nature: Museums, Collecting, and Scientific Culture in Early Modern Italy; Athanasius Kircher: The Last Man Who Knew Everything; and with Pamela Smith, ed., Merchants and Marvels: Commerce, Science, and Art in Early Modern Europe.