Investigating the Origins of a Spencer Monocular Microscope

S. Perry Post, M.D., donated this Spencer monocular microscope to the P. I. Nixon Medical Historical Library in April 2001. Little information was provided about the microscope upon its delivery. Dr. Post merely stated that he purchased the microscope, second hand, from an upper classman when he entered medical school (UTMB, Galveston) in 1934. Preliminary research revealed very little following the microscope’s arrival. When the Spencer microscope was donated, both the date of manufacture and the original price could not be determined, and no record of the Spencer Company could be found. But it is still in perfect working condition, though a little dusty. So, exactly how old is this microscope? This is the question surrounding the mystery of the microscope.


Pieces of the Puzzle

Initial inspection of the microscope and its accessories revealed a label with “Spencer Lens Company” located on the rack and pinion connected to the body-tube. “Spencer Buffalo U.S.A” is also printed on the lid of the objective lens canisters with the corresponding objective lens size: 16mm, 4mm, 1.8mm.

Recognized as the first American to successfully make microscopes in the U.S., Charles Spencer published his first catalog in 1838. In 1865, he founded the company C.A. Spencer & Sons in Canastota, New York, but moved the business to Geneva, New York in 1873 to manufacture microscopes for the Geneva Optical Co. These instruments were marked “C.A. Spencer & Sons for Geneva Optical Company.” Following the death of Charles Spencer in 1881, the business was carried on by his son Herbert, who moved the company to Buffalo, New York in 1890. From 1890 to 1895, the company was known as Spencer and Smith, but changed to the Spencer Lens Company in 1895. The Spencer Lens Company remained in Buffalo, New York. In 1935, the Spencer Lens Company was bought by American Optical but continued operation under its own name, after the acquisition, until 1945 when it became known as the Instrument Division of American Optical Company.

What does this mean for our Spencer monocular microscope? It means that it could have been manufactured any year between 1895 and 1934. To add more mystery to the microscope’s history, a mechanical stage adjustment with a “C” mount is attached to the stage of the Spencer microscope. “Bausch & Lomb Optical Co. Rochester, N.Y. U.S.A.” is engraved on the mechanical stage adjustment. B&L Optical Co. was established in 1874 and patented the mechanical stage “c” mount in 1897. The “c” mount may have been attached to the Spencer microscope following its production. Since the “c” mount is adjustable vertically and horizontally, it was adjusted to reveal two holes on the stage. These two holes indicate that the original stage clips may have been removed and replaced with the mechanical stage.

Spencer Monocular Microscope, mechanical stage "c" mount and holes for the original stage clips


Was the Spencer microscope manufactured after 1897, when the mechanical stage “c” mount was available? Or, was the Spencer microscope manufactured before 1897? The microscope’s owner may have replaced the original stage clips with the mechanical stage “c” mount after its purchase. A precise date of manufacture has yet to be determined.





Physical Description

Housed in a well-built wooden case, the microscope is black and bronze and has a rectangular pillar that sits on a horseshoe base and supports the limb and the fixed stage. The body-tube has a rack and pinion for coarse focusing and carries objective lenses with different focal lengths screwed into a circular, triple nosepiece. The micrometer screw on the bottom of the limb (under the pinion for coarse focusing) is used for fine focusing. The swing out substage consists of a condenser, iris diaphragm and filter holder. The swing out double mirror is attached beneath the stage. The microscope stands approximately 10″ in closed position and approximately 14″ fully extended.

In addition to the monocular microscope, the case houses a four-hole, eye-piece container holder, and an objective lens canister holder with three objective lens canisters. These canisters are used to immerse the eye-piece (objective lens) in oil or water. For high magnification applications, an oil-immersion objective or water-immersion objective has to be used. The objective is specially designed. Refractive index matching oil (or water) must fill the air gap between the front element and the object to allow for greater resolution at high magnification.

How old do you think this Spencer monocular microscope is? If you have a guess or any comments or questions, please contact Mellisa De Thorne at or call 210-567-2470.


Trinaé Weldy, Special Collections Intern


References and Additional Information:

“995.3.1: Microscope, Monocular, c. 1890.” British Columbia Medical Association: Medical Museum. British Columbia Medical Association, 2007-2008. Web. 21 November 2013. <>.

“American Optical/Spencer.” Robert A. Paselk Scientific Instrument Museum. Humboldt State University, Department of Chemistry, R. Paselk, 04 Feb 2009. Web. 18 November 2013. <>.

Van Vleck, Richard, ed. “Bausch & Lomb – Microscope Makers.” American Artifacts: 19th Century American Microscope Makers. American Artifacts, 1999. Web. 20 November 2013. <>.

Van Vleck, Richard, ed. “Charles A. Spencer – Microscope Maker.” American Artifacts: 19th Century American Microscope Makers. Greybird Publishing, 1999. Web. 20 November 2013. <>.