Toy "Furnace" Miniature Microscope, ~1870-1900
This microscope is merely 7.5 cm tall. The top of the box has a dovetailed slot to receive the base of the microscope. This way the miniature instrument is enhanced and stabilized which facilitates its use. Shaped as a typical French "microscope à tambour" (drum microscope), with the typical accessories that accompany these instruments, it is undoubtedly French. Yet the maker and date of manufacture of this instrument are uncertain.
Microscopes of this kind are rather common and often appear in collections and on the antique scientific instruments market. They are normally made of brass, having three or two button objectives (probably achromatic) and often, as in this case, a sleeve with two fixed knurled buttons that can be slid downwards to hold the slide pressed to the tiny stage (Balasse). They are often referred to as "furnace microscopes" perhaps due to their overall shape slightly resembling of a 19th century furnace (Microscope-Antiques).
The authors of The Billings Microscope Collection of the Medical Museum at Walter Reed Hospital (Billings) attribute the manufacture of what is then referred to as "mineral or furnace style microscope" to a certain François Bertrand, French optician, dating it to about 1840. It is unclear to the present author who was this Bertrand, and the writers of the Billings collection catalogues do not present any further data. It is undoubtedly not Émile Bertrand (1844–1909), the French mineralogist and co-founder of the Société française de Minéralogie, designer of the lens on the polarizing microscope to determine the position of the optical axes of a crystal, as well as some refractometers. The only other reference to such name that we found was to Sergeant François Bertrand (1823 – 1878), aka the Vampire of Montparnasse, who was arrested in 1841 for necrophilia. But he was undoubtedly not the maker under discussion.
In any case, the date given by the Billings catalogue is undoubtedly too early. These microscopes can be roughly dated to the second half of the 19th century, but specimens such as the one seen here can easily be attributed to the early 20th century, as evident by the nickel plating, the wood of the case and the accessories. It is high time to let the references to Bertrand and the furnace rest when regarded with this microscope, and define it as a toy case-mounted miniature microscope or any such nickname. This is not unique, as in other places in this website I suggested to omit other archaic and inaccurate terms such as "Wilson screw-barrel microscope", "Ellis aquatic microscope", and so forth. And at the same time, a new and updated catalogue with sharp color photos and modern scientifically-based dates and attributions should be published of the Billings collection. One may hope that The Walter Reed Army Medical Center and the United States Army Medical Corps can dedicate a small fund for this purpose.