The microscope is cased with a number of accessories
that include three eyepieces numbered I-III and five objectives
numbered 0, 1, 7, and two 3's. The 0, 1, and one of the 3 objectives
are signed "Belthle & Rexroth". One number 3 objective is now
defective (its front element is now mounted backwards!) and it was
presumably replaced by the original owner with another number 3
signed "Belthle". The number 7 objective is unsigned but is engraved
with the number "1337"; this lens appears to be a later addition
although it has the same non-standard thread as the other
objectives. Also included is a substage Nicol prism that mounts onto
a dovetail slot located on the mirror arm and an analyzing prism
that mounts within the body tube by screwing into the back of the
nosepiece.
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. An accessory substage apparatus
slides into a dovetailed fitting under the stage. This apparatus
holds an aperture stop which can be moved up or down relative to the
specimen by means of a lever.
This is an example of the largest size model produced
by the firm; See the Belthle and Rexroth Price list for 1862. Unfortunately,
the production archives retained by Leica Microsystems GmbH of
microscopes made in the early period of the Optical Institute in
Wetzlar do not have an entry for this microscope and therefore the
original purchaser will remain unknown. It was purchased for this
collection in the USA. Another example of this model with a consecutive serial No.
452 was also purchased in the USA. This latter example lacks the ability to mount the accessory
substage apparatus. It is no longer in this collection.
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.