Yawman & Erbe Rochester N.Y., c. 1884

Engraved on the fine adjustment knob: Pat. Aug. 15, 1882

text text
text text
Yawman & Erbe Rochester N.Y., c. 1884. Engraved on the fine adjustment knob: Pat. Aug. 15, 1882. Accessories

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.


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.

Yawman & Erbe Rochester N.Y., c. 1884. Engraved on the fine adjustment knob: Pat. Aug. 15, 1882. Storage case
Yawman & Erbe Rochester N.Y., c. 1884. Engraved on the fine adjustment knob: Pat. Aug. 15, 1882. In storage case

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.

Gundlach College Microscope

Yawman & Erbe Rochester N.Y., c. 1884. Engraved on the fine adjustment knob: Pat. Aug. 15, 1882. Storage case

Schmidt & Kaelber of Rochester N.Y.

Yawman & Erbe business

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.

Gundlach Student Microscope No1

Home-Antique Microscopes       Site Index

email: wissnera@verizon.net