A Huge Compass Microscope, ~1740
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.
The early type compass microscope seen here is exceptionally big, measuring altogether over 30 cm long. So far, this is the only example of this size known to us. Other compass microscopes, defined as "large", did not exceed half the size of this specimen. While it was acquired as part of a large collection of old junk in a UK auction, its country of origin is unclear and it may very well be of a continental European origin. Therefore, so far the maker and provenience of this exceptional instrument remain unknown.