LATERAL C-LIMB MICROSCOPE BY R. KRUGELSTEIN

DESCRIPTION:

The all lacquered-brass instrument is unsigned but obviously by Krugelstein as is clear from many features of the instrument. The microscope arises on an I-shaped pillar from a typical horseshoe-shaped continental foot. The serial number is on the upper plate of the parallel linkage mechanism as shown in the image to the left. This contrasts with the other Krugelstein Microscope in this collection where the serial number is on the bottom plate and there is a signature on the top plate. The limb can incline from the vertical to the horizontal. The substage apparatus consists of a rotating conical wheel of apertures attached to the underside of the stage by a screw. The 'lateral-C' limb above the stage allows the fine focus knob to project downward, acting on the parallel linkage fine focus mechanism above. Coarse focus is by straight rack and pinion in contrast to the later Krugelstein microscope in this collection which has diagonal rack and spiral pinion focusing.   Accessories include the two different condenser fittings, three eyepieces (numbered 1, 3, and 4), and four original objectives (numbered 3,4,7 and 10) supplied in a separate little box. The box appears to be covered in fishskin with purple velvet over cotton lining the lid and the wooden fitting within apparently made of walnut. There is a working catch to hold it closed. These objectives, like others supplied by Krugelstein, are of smaller diameter than the RMS standard, and these in particular are female threaded rather than the customary male threads. The other Krugelstein microscope in this collection has male-threaded (but still non-RMS sized) objectives. The brass optical tube is fitted with a brass drawtube. The gimbaled substage double-sided plane and concave mirror is on a swinging tailpiece, allowing oblique illumination. The original fruitwood case features brown velvet cloth cushions over the wood fittings. There is a compartment under the microscope which is empty.

Another very similar model was sold on Ebay in 2014, but had a triple nosepiece and did not have an inclination joint. Because of the triple nosepiece, it had male threaded, rather than female threaded objectives.

HISTORY RELATING TO R KRUGELSTEIN AND FEATURES OF THIS MICROSCOPE

Krugelstein is one of the lesser-known German microscope makers of the late 19th and early 20th century from about 1875 to the early 1900's. Stands by this firm are rather uncommon. There are no Krugelstein microscopes in the Billings Collection, and most private collectors do not seem to have one. Krugelstein microscopes are known for the downward facing fine focus control inside a C-shaped limb above the stage that curves to the side rather than to the back, as in most microscopes.

The downward pointing fine focus is found under the limb above the stage in microscopes by many makers, including Baker (Nelson Model), Sidle (ACME No. 4), and others, but only in Krugelstein models does the limb form a lateral curve.

The parallel linkage fine focus mechanism was apparently invented by Gundlach and/or the Seiberts when they were all working together; it was used by Seibert for many years after Gundlach left for the United States. This type of fine focus was also used by Lietz in Germany and even by Walter Bulloch in the U.S.A. on the Bastin-Bulloch microscope. In the example by Seibert in this collection, the fine focus knob is under the stage and the pillar is a lateral-facing C., as opposed to the lateral-C shaped limb above the stage found on Krugelstein stands. Many other German makers used the lateral C form of pillar this way, but apparently only Krugelstein used a lateral C form of Limb.