Joseph Zentmayer was born in Mannheim, Baden, Germany, on March 27, 1826. He worked for instrument makers in Germany eventually becoming a master instrument maker and optician. He left Germany and migrated to America, moving first to Baltimore and Washington, DC. Eventually he opened a shop in 1853 at the corner of 8th and Chestnut streets in Philadelphia. Some time later Zentmayer moved to 147 South Fourth St in Philadelphia, where he conducted his business until his death in 1888. See this article for a thorough description of Joseph Zentmayer.

This microscope is a brass monocular microscope with a claw-foot base. It is hinged in the middle with a compass joint. Attached to the main support is a descending piece that holds the Abbe condenser and mirror. The sample stage is pined to the top of this piece. The top of the stage is a glass platform with an interesting thumbscrew friction device. The microscope body is attached to the support via a dovetail slider. Mounted to the slider is the rack & pinion course focus. Fine focus is accomplished via a lever and fine-pitch thumbscrew. The microscope optics consist of a Huygens-type eyepiece and achromatic objective. The base is signed "J. Zentmayer, Phila., Patd. Aug. 15, 1878. Imaging is very good and shows no chromatic aberration. Unfortunately there is only one objective with this instrument. The number "10" is stamped in several places on the microscope.

Thanks to Ms. Riley Maxon for professional photography services.