MONOCULAR SINGLE POWER COMPOUND MICROSCOPE
MAKER:UNKNOWN
c.19th to 20th C.
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DESCRIPTION: This is monocular compound microscope that appears to be heavily modified, perhaps assembled from multiple parts.
It has an optical tube and foot resembling French makers and a clearly original mechanical stage with controls for X and Y movements. There is also a sprung lever that raises the stage clips. Coarse focus is by straight rack and pinion. Fine focus is by a thumbwheel on the optical tube. Optically, there is a single fixed objective and a single eyepiece. The microscope produces a fairly good low power view. There is a single gimbaled substage concave mirror on a swinging tailpiece which has a slot so the mirror can be moved up the tailpiece and angled for very oblique illumination.
The most interesting and unique feature of this microscope is its unusual mechanical stage. A round knob with a set screw to the right of the stage controls right-left motion in the X axis by a fine screw. A lever on the left side of the stage rotates a knob to which is attached a disk. The hole in this disk engages a pin on the stage so that as the lever is pushed forward or backward, the stage moves in the opposite direction-a handy feature since the image in the microscope, as in most microscopes, is reversed. This kind of movement was invented by Cornelius Varley, but the mechanism here is only in one direction and functionally inferior to Varley's method. The limb inclines via a joint on a short pillar at the bottom, near the foot. It can be inclined from vertical to horizontal, and anywhere in between.
CONDITION:
This microscope was received in only fair condition. Many of its parts are apparently custom-made or scavenged from other parts and there are several soldered repairs done in a most unprofessional manner, though most are not easily seen now. The fine focus mechanism attaches to the tube which carries the main optical tube and this joint is sloppily soldered. When I got it, The screw holding the gimbal for the mirror was a modern sloppy soldered replacement and I replaced it with a more appropriate brass screw. The screw holding the tailpiece to its bracket was also a modern sloppy replacement and I also replaced that. The bracket that holds the tailpiece under the stage was loosely soldered on rather than held on by screws as it should be; after it fell off, this had to be resoldered properly. The microscope was missing one of the two stage clips which was fabricated and replaced.
The rack and pinion coarse focus works well, but as expected with such a repair, the fine focus, though working, causes some image shift. The mechanical stage movements all work though the right-left movement is very fine, and the movement in the Y axis is both coarse and has a limited range. The Y axis movement is not smooth because there is no provision to adjust the fit of the dovetail of the stage plate and so the fit is not optimal.
Optically, it is a relatively low power system but provides clear, distinct images though the fine focus is difficult to use due to image shift. The system is made from parts in such a way that no other objective can be used with this scope, as the fitting for the objective is push fit. The inclination joint works well, though again the screw seems a modern replacement.
HISTORY:
Nothing is known of the history of this microscope but it likely dates to the period of 1890 to some time in the 20th century, though some parts may be earlier and some parts later.
