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THE INTERNATIONAL MICROSCOPE, IMPROVED MODEL

c. 1895

SIGNED:M. PILLISCHER LONDON, THE INTERNATIONAL, MANUFACTURER with the word TRADE to the left and MARK to the right of THE INTERNATIONAL on the attached oval plate.

SERIAL NUMBER:5710

AUTHOR: Barry Sobel

EDITOR: Joe Zeligs

Please Click On Any Picture for a Larger Version

Microscope

Microscope

Microscope

DESCRIPTION:
This bar-limb microscope weighs about 5 lb. It is based on a Y-shaped foot with twin straight uprights. It is about 10.5 inches high in the working slightly inclined position with the drawtube closed. It is about 2 inches higher with the draw tube fully extended. The outer edge spread of the two front toes is about 3 3/16 inches. The distance from the rear of the foot to the front toes is about 4 1/2 inches. The oval signature plate is attached to the foot.

Coarse focus(left) is by rack and pinion with the newer spiral pinion and diagonal rack introduced by Swift in 1881. Unlike other bar-limb microscopes, the part supporting the bar (arm) is not a single piece of brass. The coarse focus knob acts on the rear part of this divided brass bar. Fine focus(right) is via a screw on top of the rear area of the bar (arm). When the coarse focus is used, the front portion of the bar-support moves with the coarse focus; however this front portion is sprung; as the fine focus screw is tightened, it pulls the front portion closer to the top of the back part of the support which is the part the rack is attached for coarse focusing. Loosening the fine focus allows the bar(arm) to rise due to the pressure of the spring pushing it upwards. Note that the knurled disk below the fine focus screw is the top of a tube attached to the rear part of the support where the coarse focus rack is attached; the fine focus screw runs through this tube, screwing into the part of the brass block that this tube is attached to. This arrangement keeps the alignment accurate while the fine focus is adjusted, as the hole in the horizontal portion of the fine focus block allows it to ride up or down around the tube enclosing the screw. This is a very accurate fine focus which does not allow any image shift. Since it is farther away from the optical axis than a nosepiece fine focus mechanism, as it wears the image shift would be greater than the same amount of wear on a nosepiece fine focus mechanism.

There is a draw-tube, which allows the tube length to be varied to accomodate English or German standards. Closed the length of the tube without objective or eyepiece is about 5 3/4 inches(140 mm), and fully extended, 8 inches (200 mm). The main outer optical tube can slide in the sleeve on the arm. There is a single objective with an approximate focal length of 1/4 inch which is unsigned,and a single eyepiece labelled 3.

Attached to the bottom of the stage via a screw is the wheel of apertures. There is a gimbaled plane and concave mirror on a arm that can swing side to side. The microscope can incline from vertical to horizontal. There are two stage clips on the top of the stage and a wheel of apertures with a spring stop screwed to the bottom of the stage, controlled from the right side of the stage.

HISTORY OF THE PILLISCHER INTERNATIONAL MICROSCOPES:
Moritz Pillischer emigrated from Hungary to London, England in 1845. By 1848 or 1849 he was selling microscopes and other scientific instruments. His supposedly earliest microscope was pictured in Quekket's 1852 Practical Treatise on the Use of the Microscope. Moritz’s nephew, Jacob (later James), joined the firm about 1860, taking over in 1887. The company was later inherited by Jacob’s children, and the business was liquidated in 1947 after about 100 years of business.

The International microscope, a basic bar-limb design, sometimes supplied with attached bulls-eye condenser, was introduced about 1876. It was named the International because of its draw tube allowing adjustment of the tube length for English or Continental objectives. It was used with the draw tube extended for English objectives or closed for use with Continental objectives which were designed for a shorter tube length. It was widely advertised, produced for many years, and apparently quite popular, as many examples still exist. The model changed a bit over the years. My example has a rectangular profile to the bar support which is split, but prior models had other profiles. For example, an International with serial number 3462, had a solid support with a pentagonal profile in which two sides of the pentagon are parallel; it also has a straight rack and its fine focus mechanism is different than my example shown at the top of this page. The example on this page, made about 20 years after the model was first introduced, has no bullseye attached but has the diagonal rack, as introduced by Swift in 1881 (and copied by most other makers). The International model continued to be sold and advertised for more than fifty years, even as late as 1930, which is not surprising considering the quality of its construction and its relatively compact size.

CONDITION:
This microscope is in excellent mechanical and cosmetic condition and works very well. Despite its size it is an impressively well-made microscope with no flimsy parts, making it suitable for low to fairly high magnification, though the fine focus threads are not fine enough for easy focusing with the highest powers. There is no major shift in focus when using the coarse or fine focus and it is easy to use at moderately high powers. The case it came with is not likely to be the original, and although physically sound, unlike the microscope itself, it is not in good cosmetic condition. The finish of the case has damage and stains and the hinges as well as the catches are rusty.

FOR MORE INFORMATION ABOUT VARIOUS PILLISCHER MICROSCOPES SEE THE HISTORY SECTION OF THE PAGE ABOUT PILLISCHERS EARLY LARGE MICROSCOPE.

FOR MORE INFORMATION ON THE HISTORY OF THE PILLISCHER FIRM PLEASE SEE BRIAN STEVENSON'S THOROUGH DISCUSSION ON HIS EXCELLENT WEB SITE.