Historical story

What did Zacharias Janssen do?

Zacharias Janssen (c. 1580/1585 – before 21 November 1632) was a Dutch spectacle-maker who is commonly credited with making the first compound (multi-lensed) microscope around 1590 in Middleburg, Zeeland in the United Provinces (the present-day Netherlands).

The earliest historical account describing how the microscope arrived in Rome states that an anonymous traveler arrived there in mid-September 1609 at an inn located just off the Piazza Rotonda with "many wonderful instruments including two eyeglasses [microscopes] of wonderful craftsmanship by means of which even fleas appeared like monsters twenty feet tall". Galileo mentioned having learned of the existence of the instrument "this past October" [1609]. Dutch travelers had been in Venice just before their arrival but there were also Dutch colonies near Rome; these travelers and Dutch diplomats may have spread knowledge of and introduced examples of Janssen's instrument.