R. Fuess, Berlin - Steglitz, #1550

Model IIIa petrological microscope with mechanical stage, c.1908

 

R. Fuess, Berlin - Steglitz, #1550. Model IIIa petrological microscope
R. Fuess, Berlin - Steglitz, #1550. Model IIIa petrological microscope
R. Fuess, Berlin - Steglitz, #1550. Model IIIa petrological microscope
R. Fuess, Berlin - Steglitz, #1550. Model IIIa petrological microscope
R. Fuess, Berlin - Steglitz, #1550. Model IIIa petrological microscope
R. Fuess, Berlin - Steglitz, #1550. Model IIIa petrological microscope

This is an example of the Fuess Model IIIa. It is made entirely of brass with bright lacquered, black enameled, and nickel plated surface finishes. Coarse-adjustment is by rack and pinion. The fine-adjustment is by micrometer screw located at the back of the limb. The end of the body-tube carrying the objective is movable by two screws for centering. To facilitate the change of objectives, the latter are not screwed on, but held by a clamp. Immediately above the clamp is a slit for the introduction of a Klein’s plate, quarter-wave plate, etc. The stand measures about 15-inches tall inclined as shown in some of the photos. The rotating stage is divided into 360º, with verniers reading to 5 minutes. This particular example is furnished with the mechanical stage that is usually associated with the Model II having calibrated movements. The sub-stage, which focuses by rack and pinion, holds a polarizer and a three element condenser. The top two elements can be moved aside for low power work using a lever mounted on the side of the stage. The analyzing prism in mounted on a slide within the tube as is the Bertrand lens which can be focused manually by moving it within the tube. The mirror is mounted an arm which is moveable side to side.

Fuess accessories
Fuess mechanical stage Fuess mechanical stage

The microscope came equipped with one eyepiece. Stored within a leather covered box are four objectives numbered 0, 2, 4, and 7, two glass compensator plates, and the quartz wedge mounted on glass. An earlier version of the Model III from 1893 is also represented in this collection. The version shown on this page differs from the earlier version mainly in having a larger size, in the shape of the limb, and in the use of a wider tube taking a 30 mm ocular. The mechanical stage on the microscope is an additional refinement, not normally supplied with the standard model IIIa.

A trade card attached to the door of the case indicates that the microscope was retailed by Charles X. Dalton, Boston.

in case case

 

signature

Another example of this microscope with the conventional stage is located at the National Museum of American History.



This microscope was purchase from the great-grandson of the original owner, Dr. Milton K. Thompson. Dr Thompson's practice was in Muskogee, Oklahoma area. His speciality was ear, nose, and throat surgery. It would seem that he may also have had an interest in geology/mineralogy.

About the maker Heinrich Ludwig Rudolf Fuess (1838 - 1917)

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