J. & W. Grunow, New Haven Ct, No. 196

The Student's Larger Microscope, c. 1855

J. & W. Grunow, New Haven Ct, No. 196. The Larger Student's Microscope, c. 1855

J. & W. Grunow, New Haven Ct, No. 196. The Larger Student's Microscope, c. 1855

 

This microscope likely dates from the mid-1850's. The Grunow brothers, Julius and William, emigrated from Germany to New York around 1849. They started in the scientific instrument business by first working for the optician Benjamin Pike of that city. By 1854, they began their own operation in New Haven CT where they concentrated on the production of microscopes. By 1864, they were back in New York. Some years later, the partnership ended. J. Grunow continued on to produce microscopes up to around 1892. The total output of the Grunows was limited in comparison to some other contemporary firms; on the basis of the observed serial numbers, they manufactured just over one thousand microscopes in total.


The following was extracted from the Illustrated Scientific and Descriptive Catalogue of Achromatic Microscopes Manufactured by J. & W. Grunow & Co., New Haven, Conn, 1857

J. & W. Grunow Larger Student's Microscope

The Student's Larger Microscope. Shown in figure 10, is made of the dimensions agreed by microscopists as the most convenient for general use, and fitted for the application of accessory apparatus of such dimensions as to secure their greatest desirable efficiency. The tripod base is large and strong made of japanned cast-iron, giving firm support and freedom from tremor. The coarse adjustment is performed by rack and pinion, by turning a large milled head, conveniently placed; the body moving steadily in a long grooved support, and being retained in any position by springs. The fine adjustment of the focus is performed by a screw acting upon a lever, which gives to the stage a delicate upward movement. Two sliding clips retain the object on the stage.

The stage, which is three by four inches, is so constructed that it can be moved smoothly and steadily in every direction, the object appearing to follow the motions of the stage upon the lever. This movement of the stage gives great facility for tracing every part of the slide in the search for delicate objects, and enables the observer to follow with ease the motions of living animalculae, even with high powers. Beneath the stags is circular plate carefully centered and adapted for receiving accessory apparatus. Two mirrors, plane and concave (the latter two inches in diameter), are so mounted as to have a free and steady motion in every direction. By means of an arm, the mirrors can be thrown far out from the axis of the microscope to give very oblique light for illuminating the object.

This instrument has a graduated draw-tube, by which the distance between the objective and eyepiece can be considerably increased. This increased length produces a proportional increase of the magnifying power, and thus often greatly aids in ascertaining the value of micrometer graduations*

Stage Movable by Rack and Screw. American microscopists generally prefer our form of stage, movable by a lever. The instruments that we keep on hand are, therefore, usually furnished with this form of stage. But we are accustomed  to make to order a stage movable in two rectangular directions by rack and screw.


* This instrument is often made with a plain stage, which considerably reduces the expense. It can also have added the revolving motion of the stage, as shown in the next figure. Bailey's Indicator Stage can be applied to this instrument, if desired, instead of the stage here shown. The use of cast-iron, for the base and arm of the preceding instruments, has been adopted to bring the prices within the most reasonable limits. This arrangement does not, in any manner, diminish the efficiency or beauty of the instruments. The parts made of iron are carefully smoothed and neatly japanned, and give a pleasing contrast of color with the other parts, which are of brass. But when specially ordered the base and arm are also made of brass, at a reasonable addition to the price.


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