Large microscope on a double pillar with swinging substage, c. 1880
The accessories supplied with this microscope include two Hartnack objectives, an objective by W. Wales with canister, another unsigned objective marked 1/4 with canister, three eyepieces, a substage Abbe condenser with iris diaphragm and filter holder, two glass filters, a substage aperture stop holder with one stop, a brass substage adapter, a live box, a double objective changer, and for polarization work a substage polarizer and an analyzer that mounts above an objective. The stage utilizes a brass and glass slide carrier.
Leopold Schrauer first began the manufacture of microscopes in the late 1850's in Boston. By 1877, he was located in New York City. Schrauer microscopes are relatively uncommon, this model in particular, which is the only example that I have seen in 40 years. In the book entitled A Short History of the Early American Microscopes by D. Pagitt, it is stated "It is somewhat strange that Schrauer's microscopes are not more common today, since
he was apparently in business for more than 20 years. This may be partially explained by Schrauer's proclamation that he gave no discount to the trade which would indicate that he did not have access to the traditional marketing agencies". Schrauer did not use serial numbers for his microscopes. As a consequence of this, it is often difficult to date them precisely. Most likely this microscope was made sometime in the late 1870 to early 1880 time period. While an 1878 advertisement lists Schrauer at
50 Chatham St. NY, an 1879 advertisement lists him at 42 Nassau St. NY, the address on this microscope. Later Schrauer microscopes are mostly in the continental style.
This microscope is probably the largest model microscope that Schrauer ever produced. It is quite massive measuring about 18-inches in height inclined as shown in the photos with the draw-tube closed. It borrows some features present in Zentmayer’s American Centennial model, which was introduced in 1876. Among these features are
the mounting of the microscope on a double pillar attached to a tripod base. However, unlike with the American Centennial
where the fine adjustment moves the tube
with the limb remaining stationary, the fine adjustment on this Schrauer moves both the limb and the tube together. The microscope’s sliding brass and glass slide carrier is also reminiscent of those used on Zentmayer microscopes. The most notable Zentmayer innovation found on this microscope is the calibrated swinging substage. While Zentmayer was not the first manufacturer to incorporate a swinging substage, the main purpose of which was to allow oblique illumination, he popularized this innovation with the
introduction of the American Centennial model. One other feature of this microscope includes a centerable sub-stage that focuses by rack and pinion