The Compass Microscope, 1700-1830
The "Compass Microscope" is named so because of the center hinge, reminiscent of a drafting compass. It was used during the 18th century for inspecting small opaque objects such as fauna or flora. To use the instrument, the user would mount the specimen with the stage forceps and locate it just opposite the lens. The silvered reflecting Lieberkuhn mirror focuses more light on the top surface of the specimen. These microscopes were very popular as pocket field aids for naturalists.
This type of compass microscope appears in the popular book by Henry Baker (1698-1774), The Microscope Made Easy (1743), as a microscope for opaque objects. Using the compass microscope as a basis for the design, this microscope incorporated a hinged focusing system with a reflector or speculum that reflects light upon the object making it possible to examine opaque as well as translucent specimens. The parts and functionality are explained further in chapter VII, entitled "Of the microscope for opake [opaque] objects." Baker's book popularized the microscope in the 18th century.
Compass Microscope Set, ca. Mid-18th Century (Inv. YG-21-004)
This is a typical early set brass compass microscope of the mid-18th century. It has a brass body with turned handle, a sliding and pivoting specimen holder, forceps and a live box that opens on a screw hinge to hold small specimens. The microscope includes four varied Lieberkühn eyepieces with very early turned horn inserts to hold the lenses in place, brass tweezers, one wood eyepiece, and a small "talc box" cylindrical container holding mica cover discs.
Small Folding Compass Microscope, ca. 1750 (Inv. YG-20-032)
The early type compass microscope seen here is exceptionally small, measuring altogether about 10 cm long. So far, this is the only example known to us. So far the maker and provenience of this exceptional instrument remain unknown.
French Compass Microscope, late 18th to early 19th Century
This late 18th-century compass microscope is often considered to be French. It elaborately features two lieberkuhns, each one having a different lens, which enables the examination of the object under different magnification. It comes with ebony-turned handle.