HARDNESS TESTER FOR USE WITH MICROSCOPE
MAKER: SPENCER
DATES of PRODUCTION: 1920's to 1950's(?)
SIGNED:'MICROCHARACTER, American Optical Co, Buffalo 15, N.Y., Made in U.S.A.'
This page shows images of the Microcharacter device from the patent papers along with a simple key list to the numbers. Note that some parts are mis-numbered in the drawings.