Materiality of Early Modern Optical Instruments

This workshop took place on 22 January 2019 at the Department of History and Philosophy of Science, Free School Lane, Cambridge. Expert curators Dr Michael Korey and Dr Tiemen Cocquyt introduced the most recent research on the materiality of historical optical instruments and their lenses. Their talks were accompanied by hands-on sessions with replica instruments. 


  • Dr Michael Korey, Curator at the Dresden State Art Galleries
  • Dr Tiemen Cocquyt, curator at the Rijksmuseum Boerhaave

New Light on Old Instruments – Recent Findings on the Optics and Materiality of Early Telescopes 

Michael Korey, Staatliche Kunstsammlungen Dresden & Tiemen Cocquyt, Rijksmuseum Boerhaave

A telescope serves as an easily recognizable scientific instrument, one with a readily understood purpose and construction. Or so it would seem. The talk will recount an intensive 3-month research expedition (with Marvin Bolt, curator at the Corning Museum of Glass) tracking down and optically measuring telescopic “incunabulae” in more than two dozen museums and private collections across Europe, which capped a decade of investigating the startling variety of early instruments. In addition to describing our methods, this richly illustrated and broadly accessible lecture will present selected key findings: the surprising quality of the oldest securely dated telescope, including interferometric analysis of its lenses; the discovery of the only two known examples of 17th-century Keplerian telescopes and their connection to painterly iconography; and the intersection of theory and craft practice in the lensmaking of Isaac Beeckman.

Telescope from the “Pommerscher Kunstschrank”, Kunstgewerbemuseum (Berlin), before 1617:

Image: Marv Bolt
Detail of the main tube and first draw
Image: Michael Korey & Marv Bolt
Detail of main tube and objective (photo: Michael Korey/Marv Bolt)
Image: Tiemen Cocquyt
Ronchigram of the objective lens (photo: Tiemen Cocquyt)







Images from the hands-on session with replica telescopes for use in direct observation and solar projection:

Blown, Ground, Flame-Worked, or Dropped? Interrogating the Lenses of 17th-Century Simple Microscopes

Tiemen Cocquyt, Rijksmuseum Boerhaave & Michael Korey, Staatliche Kunstsammlungen Dresden

The single-lens (“simple”) microscopes made and used by Antoni van Leeuwenhoek in the years 1672 – 1721 have acquired iconic status in the history of 17th-century science for their role in fundamental microbiological discoveries. Yet surprisingly little is known with certainty about the composition and construction of the key component of the ten or so surviving instruments of this type: the tiny glass lenses mounted between thin metal plates, with a free aperture of only 1 mm or less. Were they ground, as Leeuwenhoek himself claimed, flame-worked, or produced by some other method? A combination of approaches – empirical trials with master glassworkers, innovative material analysis, and a re-examination of contemporary archival sources – leads us to question traditional accounts of these lenses. In particular, we look closely at the work of the Amsterdam regent Johannes Hudde (1628-1704), whose introduction in the 1660s of flame-worked, solid globular lenses, rather than the ground glasses of lenticular shape common until then, strikingly re-oriented Dutch microscopic activity. In what technological context did Hudde’s lenses emerge? How did the optical properties of his lenses differ from those of his predecessors? Did his lenses arise from practical experience, from developments in theoretical optics, or in a way that might be situated outside the optical tradition? While addressing these topics in the context of 17th-century glass technology, some points become clearer, new questions emerge, but the meaning of a contemporary “Dutch joke” remains to be resolved.

Replication of Hudde’s globular lenses and of blown lenticular lenses:

Image: Corning Museum of Glass
Image: Corning Museum of Glass
Image: Corning Museum of Glass
Image: Corning Museum of Glass
Image: Corning Museum of Glass
Image: Corning Museum of Glass







Images from the hands-on observing session using replicated single-lens microscopes. Photographs of the optical instruments with kind permission by the Whipple Museum of the History of Science, University of Cambridge: