112x brass

This microscope is #5 in van Zuylen and Bracegirdle.

The focusing screw is missing.

The eyeside view shows a second hole in the L-bracket. Because of the length of the positioning screw, it doesn't matter where the bracket is attached to the body plates. As long as the L clears the bottom edge of the body plates, the positioning screw will be able to raise and lower the mount and specimen. It would be interesting to compare the size of this hole to the size of the hole that Leeuwenhoek ended up using. If this one is larger, perhaps he used a drill that was too wide for the tap and die he was using for the screws.

Note that the 266x brass microscope above, the most powerful, has a similar extra hole in the L-bracket as does the 110x brass microscope below. All three of the holes are filed smooth, as compared to the hole in the body plate of the 68x silver microscope.

In 1906, the Deutches Museum, in Munich, requested from Utrecht University a replica of the their Leeuwenhoek microscope, the 266x brass. Instead, Marinus Pieter Filbri (1852-1917), amanuensis of the physics laboratory of Utrecht University from 1889-1917, sent three originals in October 1906. He had acquired them, two silver microscopes and a brass microscope, from his ‘family, friends, acquaintances and fellow craftsmen’. This account comes from Franz Fuchs's "Der Aufbau der Physik im Deutschen Museum 1905-1933" (Deutsches Museum, Abhandlungen und Berichte 25:3 (1957), p. 22) and is recounted in Van Zuylen's, "On the microscopes" (p. 170, 189).

Filbri was born in Delft and apprenticed there at the P.J. Kipp scientific instruments factory. It indeed is plausible that through his Delft network he found some of the many microscopes spread in 1747 among Delft residents. As noted in Ford's Leeuwenhoek Legacy (p. 139), the two identical silver microscopes (evidently a pair as auctioned in 1747) have characteristics resembling the description of the missing microscopes of the Royal Society.

In 1911 the Deutsches Museum exchanged one of these microscopes with the Zeiss Museum in Jena. Unfortunately the Jena-instrument is missing, probably since World War II. Only some photographs have been preserved, according to a personal communication in January 2015 from Hans Meinl of the Optisches Museum Jena der Ernst-Abbe-Stiftung.

Thus, of the three microscopes that the Deutsches Museum received for a bargain price in 1906 from a lab in Utrecht, one is now lost, another is the 167x silver microscope, and the third is this brass microscope, still at the Deutsches Museum.