The microscope is cased with a single objective and three eyepieces. The rectangular stage has an oxidized brass finish and there are no provisions for stage clips. Inset under the stage is a wheel with five apertures.

This is an example of the largest size model produced by the firm; See the Belthle and Rexroth Price list for 1862. It was purchased for this collection in the USA, although it no longer resides in this collection. Another example of this model with serial No. 451 was also purchased in the USA.

In 1849, Carl Kellner founded what was named the Optical Institute in Wetzlar Germany. By 1851 he employed twelve workmen and was producing his first microscopes. Kellner's microscopes met with wide acclaim and were furnished with his noted invention, the orthoscopic eyepiece. Unfortunately, at only the age of twenty nine, Kellner succumbed to tuberculosis in 1855. The Optical Institute survived under the leadership of Friedrich Belthle, an apprentice of Kellner's, who married Kellner's widow shortly after his death. Beginning in 1857 there was, for a brief time, a partnership between Belthle and H. Rexroth. In 1863, Ernst Leitz joined the Institute. By 1865 he was a partner in the firm, and later became the sole proprietor after Belthle's death in 1869. For more information about this microscope, related instruments, and the history of the Leitz firm see the article: Some Early Microscopes from the Optical Institute in Wetzlar.

A short biography of Friedrich Belthle (1829-1869) is online.