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c. 1902


SIGNED WITH PATENT DATES: 'PAT. MARCH 14, 1899' and 'PAT. DEC. 11, 1900'



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This 'Continental Style' microscope sits on a Y-shaped 'horseshoe' foot. Arising from the foot is a short pillar, to which the main body of the microscope is attached via a compass joint. Atop the microscope is a standard 22 mm diameter ocular which fits into the chrome-plated graduated draw-tube. Coarse focus is by diagonal rack and pinion (a Swift innovation). There is a patented adjustment for pressure of the outer fitting against the bearings of the coarse adjustment, which is adjusted by a silver-colored knob. The fine focus, adjusted by a silvered knob, has two patents as noted below. The smaller diameter knob allows a quick motion to the fine focus and the larger knob a slower one. There are three objectives on a triple nosepiece. The surface of the stage is of vulcanite. It has holes for two stage clips, but these have been replaced with a later mechanical stage with separate X and Y controls. This stage is attached by two thumbscrews on the right side. It is of chrome plated brass, and has verniers in X and Y axes. The substage condenser rises or falls via a helical 'quick screw' as described in the patent. This condenser can be removed from its housing; there are two iris diaphragms, one above and one below the lenses of the condenser. A patented feature prevents the condenser from being inserted into the mount unless the iris above is fully open, preventing damage. The gimballed planoconcave mirror rides on a swinging tailpiece which has a sprung catch to hold it in the vertical position if desired. The mirror carrier can also slide up and down the tailpiece. This microscope is in almost new condition.


spencer patentsCharles Achilles Spencer is generally acknowleged to be the first major maker of microscopes in America. His first were horzontal microscopes on the Chevalier plan. He then went on to produce his famous 'Trunnion Microscope' (very similar to the Ross Bar Limb), which can be seen on Alan Wisner's Website here, and his 'Pritchard type' also on Alan Wisner's Site here. Although there were eventually over twenty American Makers in the late 19th century, only Spencer and Bausch & Lomb continued to produce microscopes far into the twentieth century. The example shown on this page is an early example of his continental style 'First Class' or 'Number One' stand. It has inscribed on it the patent dates of March 14, 1899 and December 11,1900. On the latter date two patents were listed. One was for Spencer's 'quick-screw' substage mechanism which allowed adjustment of vertical motion of the substage and also allowed it to be easily swung out of the way. It was also designed in such away that the condenser could only be inserted fully into the holder when the upper iris was fully open. This prevented damage to the iris. This type of substage adjustment became a standard on Spencer microscopes as well as many others (including Zeiss) for many years. Spencer was the first to patent this type of mechanism in the United states. The patent for the substage can be seen here. But the substage was not the only Spencer patent applicable to this microscope. On the same date a patent for the focusing mechanism, the second for a focusing mechanism by Spencer in just two years. This 1900 focusing mechanism patent can be seen here. This microscope also has features for coarse adjustment from the March 1899 patent by Spencer, also a patent date on it. It is clear then, that this microscope illustrates features from three contemporary patents just before the time it was produced. By 1900, Spencer had produced about 8000 stands; but serial numbers started to be applied by the Spencer company only at around the turn of the century, and it appears that the first serial number was 1001. The first six hundred of Spencer's numbered microscopes were made with a wider optical tube and drawtube, and accepted wider eyepieces. These microscopes therefore have the serial numbers of 1001-1600 or so. After this, they have narrower tubes accepting the standard 22 mm eyepieces. The example shown here, number 1934 is therefore one of those with the narrower, standard 22 mm draw tubes to accept the standard eyepieces. The bright all-lacquered brass finish was used only for a short time, in favor of the new trend early in the twentieth century to change to an all black finish. For this reason, these Spencer microscopes with this finish are today uncommon, and even less common in good condition.
The author is greatful to James Solliday for providing me information on the early twentieth century Continental style Spencer stands and their serial numbers, and sharing his own examples of these stands, one with the earlier wider eyepieces, and another example similar to this example with the narrower 22mm opening for eyepieces.