Among the accessories are
two Gundlach objectives, a 1/4-inch and a divisible 2/3
and 1-inch objective both with canisters, two eyepieces
(one incomplete), an eyepiece micrometer, a camera
ludica, a live box, a Holman's live slide, and a set of
dissection tools. The stage can accommodate two stage
clips or an accessory glass stage with an articulated
nickel plated slide carrier. The sub-stage consists of
a wheel of diaphragms. The microscope utilizes a novel
differential screw fine adjustment.
This description of the
differential screw fine adjustment was extracted from
The Odontographic Journal, 1881. It was
patented by Philip Yawman on Aug. 15, 1882
The same gentleman
also exhibited a new fine adjustment for microscope
stands, invented and manufactured by Messrs. Yawman
& Erbe, of this city. What are commonly called fine
adjustments rarely get beyond one hundred threads to
the inch, but this a differential screw, which is a
compound screw by which a motion is produced equal to
the difference of the motions of the component screws
gives a movement equal to three hundred and sixty
threads to the inch. This exceedingly fine movement may
be reduced, by loosening a conveniently placed
milled-head screw, to sixty threads to the inch, an
adjustment sufficiently fine for all low power
objectives. This fine adjustment is attached to all
stands made by this firm, and may at slight expense be
attached to stands of other manufacture. All microscope
stands made by Messrs. Yawman & Erbe have three
adjustments: 1st. The rack and pinion common to all
good instruments; 2d, The ordinary fine adjustment as
used on first-class instruments generally; and 3d, What
may be called their superfine adjustment, the
differential screw. It was on a stand fitted with this
superfine adjustment that Major Streeter was enabled to
show off his highly-prized one-eighth objective,
which he did under most unfavorable circumstances,
resolving and resolving the Amphipleura pellucid of Mr.
Main's test-plate, a feat that with the ordinary fine
adjustment had often consumed fifteen minutes in its
accomplishment.
Philip Yawman and Gustav
Erbe were both employees of Bausch & Lomb. In 1880,
they left that firm to start their own business in
Rochester New York. For the greater part of the life of
the firm, Yawman & Erbe primarily were involved in
the manufacture of office furniture and equipment.
However, for a very brief period in the early 1880's
they manufactured microscopes. It appears that the
production of microscopes was in collaboration with
Ernst Gundlach, another former B&L employee. It is
clear that it was Gundlach who produced the optics, but
it is less clear which firm actually manufactured the
stands. Both firms often sold the same model
microscopes and, in fact, there are microscopes that
bear dual signatures by both firms. For example, see
the two
"Nonpareil" model microscopes in
this collection. Also, see
this Gundlach signed microscope which is very
similar to the instrument shown on this page with the
exception of having a cast iron base instead of a brass
base. Additionally, the walnut storage cases for all
these microscopes are distinctive and identical. The microscope
shown in the engraving taken from The Journal of the Royal
Microscopical Society, 1882 was made by Ernst Gundlach
and was named "The College Microscope". It is very similar to
the microscope shown on this page. This is another example of the close relationship between Gundlach and Y&E.
While the furniture produced by the Y&E is now
rather common, the microscopes are far less so. The
early history of the Yawman &
Erbe firm has been documented.
There are labels in the
storage case indicating that the microscope was
retailed by Schmidt & Kaelber of Rochester
N.Y.
As mentioned above, there was a collaboration between the Yawman & Erbe
and Gundlach firms in the early 1880s. Similar microscopes were sold
by both firms. For example, the Gundlach Student’s Microscope No. 1
as shown in the 1882 Gundlach catalog is very similar to the microscope
shown on this page although it lacks the differential screw feature of the fine adjustment.
However, Gundlach did use this differential screw with his College Microscope.
It was described in the catalog as follows:
The mirrors are plane and concave, the latter being two inches in diameter.
The mirrors swing above the stage to any angle for the illumination of opaque
objects, and the mirror bar is graduated in five-degree spaces. The device for
keeping the friction uniform on the mirror-bar is a new one. It is a contrivance
that keeps in order and is durable. There are three adjustments: rack-and-pinion,
sliding adjustment. and micrometer screw. The rack, which is on a double-V is
very satisfactory. It is new in design and perfect in work. The fine adjustment
is an entirely new invention. It is simpler and much less expensive than the
roller motion adjustment on the College Microscope. It will be found satisfactory,
and fully adequate to the work it is intended to do. It is worked by a milled
head on top of the pillar, and it has a very much greater extent of motion than
the fine adjustments of other makers. This stand was originally devised with
reference to receiving a glass stage. A glass stage with simple slide carrier
has been devised which can be added to the stand at small expense, making it
equal to those of greater pretensions at a much lower price.
