Back Button


Zentmayer Grand American Microscope


Zentmayer Grand American Microscope Stage Zentmayer Grand American Microscope Stage Signed in Script on the Foot: J. Zentmayer, Maker, Philad ' a . This is a well-built, heavy, lister-limb microscope incorporating a goniometer rotation to the stage and a Zentmayer gliding slide holder which runs on two slightly raised linear bars on the stage. The glider is secured via a ivory-tipped sprung control which presses on the glass plate allowing very smooth and controlled motion via the two handles on either side. Silvered scales are present on the foot at the base of the pillar, on the nosepiece control, and on the rotating stage. The nosepiece fine focus wheel is calibrated. The substage can be lowered or raised by rack and pinion. The single ocular has a slot to admit a Jackson type micrometer. The calibrated drawtube is threaded at its distal end to accept an analyzer or an erecting lens. There is a single moderate power objective signed Queen. This instrument is in the process of being partially restored, and new pictures will follow once this is accomplished.


Engraving with Grand American Scope Joseph Zentmayer was born in Germany 1826 and emigrated to the U.S.A. after receiving training in Europe. He apparently started his own business in 1853 and built his first big microscope almost identical to this one about 1858 to the design of a Dr Hunt of Philadelphia; it was still advertised in the T. H. McAllister Catalog of 1876. The Grand American was made from about 1858 through about 1876 when it was replaced by Zentmayer's American Centenial stand. The arrangement of the goniometer stage, and the gliding slide holder on it, as shown here, were both invented by Zentmayer in 1859, according to The American Naturalist of 1873. The catalog entry for 1876 of T.H. McAllister also states this type of gliding stage was invented by Zentmayer, but it dates the invention to 1862.

The Zentmayer Grand American model originally had a mechanical stage (using a fusee-chain drive for one axis), or as an option the Zentmayer gliding stage. Although Zentmayer's purported use for the calibrated revolving base was to measure numerical aperture, its purpose as described by Zentmayer's contemporary Bulloch was as a convenience for photography. When he developed his method of taking photomicrographs, Dr Joseph J Woodward, an Army Surgeon, used this model microscope for that purpose. Fully equipped, this stand was among the most expensive of American microscopes of the time,and would have sold with a full set of accessories for $700 in the 1860's; that would be over $12,000 today. For this reason, few could afford such an expensive instrument!