That one was the smallest stand they made prior to w.w. 2, that they considered a research microscope. I had a discussion with the curator of the Harvard Scientific Instruments collection about a year ago, related to this model microscope. They have one they catalogue as a #4, which due to the more complicated substage, heavier substage mounting, focusing mirror and slightly heavier body is actually a #2. In this case the reverse is true. This is a model 4.
Spencer microscopes, prior to the 2nd W.W. all have a great deal in common and there were many different models, less as time marched on but in the 1917 catalogue there were more than 30. In order to determine a model, I have had to resort to what sometimes seem ridiculous measurements. This one is pretty straight forward , though.
Spencer hardly ever changed anything on a stand, unless it was a stated option, without changing the model.They did however, shift from having many lacquered brass fittings , to having fewer chromed with some previously brass parts black enameled, sometime after 1930. This can complicate things, as was evidenced in my communication with the curator for instance. She saw, what she called " a vertical metal strip( brass focus block)" in a scan I sent her of a # 2 as proof that her instrument was not a #2, because her instrument did not have that feature. She failed to understand that by the time her microscope had been made( 1932, I believe) they had changed to enameling that part and was unable to understand the issues related to the condenser parts, etc. Last time I looked, they still mis-identify it.
In the case here, if you strip off the optional components; the head with nosepiece , objectives and eyepieces; the stage and the substage, you are left with the basic stand.
On the # 1/2 stand block carrying the coarse focus, there are concave sides. The upper part of the arm carrying the fine focus control is sharply tapered in a lengthened ellipse, coming to almost a point . The fine focus control itself has a 1 inch knob, extended on collars. They sit 1 inch out from the body and the graduations are in 1 micron increments.
The arm at it's mid point is 25.5mm deep by 23 and a bit, wide.
The stage bracket is a Y shaped flange, half lapped into an extension of the arm.
The substage itself is actuated by a rack and pinion, the shaft of which has a relief cut into the pillar. The dovetail track carrying the rack gear is 7/8" wide. The mirror focuses by sliding on a flat, track bar.
The condenser is a 1.3 N.A. achromat, with centering controls.
The entire instrument is made of brass, which can easily be seen on the soles of the horseshoe base, which is 6" x 4 3/16". It weighs between 12 1/2 and 13 lbs., loaded, depending on what accessories are added.
The microscope pictured here , if you compare it to the 1929 catalogue, pg. 4
http://user.xmission.com/~psneeley/Pers ... oscope.htm description, more closely resembles the #4. In the 1930 catalogue, it is even more apparent , because they had switched the finish to chrome and enamel,with some previously brass parts, such as the focus block being enameled. The more complex stage is irrelevant because that was an option. It has the 3/4" fine focus knob with almost for sure 2 micron increments,which is based on Spencer's travelling screw mechanism, rather than a worm and nut; a simpler lighter stage bracket, and the simpler lighter , non-centering abbe condenser and non-focusing mirror. The base is lighter and probably of cast iron too.
