Antique Spencer MICROCHARACTER American Optical Co Hardness Tester

Description

Antique Spencer Microcharacter hardness tester for microscope.  Made by American Optical Co. Buffalo NY.  This was a rare piece manufactured in the late 1920's, adjusting for inflation it sold for approximately the equivalent of 00 in 1924.  The below write up was from a 1924 catalogue.  The 6x eyepiece is included, it is missing to top horizontal bracket where the cutter would attach.
Shipping .95 USPS Priority Mail to US only.
HISTORY OF THE MICROCHARACTER:
The 'Microcharacter' was invented by Christopher Bierbaum. He submitted his request for patent on Dec 29, 1920 and he was granted patent 1.585,278 on May 18, 1926. It is one of several methods of testing hardness of metals and other materials, but at the time was one of the only ones that could do so on a microscopic scale. Apparently the 'Microcharacter' was offered in the catalogs by Spencer starting in 1924 and called the 'Spencer Microcharacter' and sold as an attachment to the stage, as shown in the catalogue. That early entry notes that the microcharacter was sold as a package with a Ramsden Eyepiece Micrometer and an electric illuminator.