Leitz petrographic 1908 | microscope-history

Withering-type botanical microscope, 1780

The “Withering-type Microscope” is named for its inventor, Dr. William Withering (1741-1799), an English physician and botanist who graduated with a degree in medicine 1766 in Edinburgh. Inspired by the taxonomical work and systematic classification of Carl Linnæus (1707-1778), Withering (1776) applied the Linnaean taxonomical system of classification to British plants in a seminal, two volume work, A Botanical arrangement of all the vegetables naturally growing in the British Isles. The earliest reference to a small botanical microscope of Withering’s design appeared in the first edition of this book. There, Withering indicated this microscope was developed for field dissections of flowers and other plant parts. While there is no surviving example of this exact design, close relatives of this type do exist, made either completely of brass or of ivory with brass pillars. Ivory models can be tentatively dated to 1776-1785, as by 1787 a newer model with a hollowed stage in an all-brass configuration already predominated. In turn, it was preceded by the brief appearance of a transitional brass model but with solid stage of ivory or horn (seen here). This version is extremely rare and must have been produced in very small numbers. By 1787 all these varieties were not recorded anymore in the literature.

Withering-type botanical microscope, 1780

Ernst Leitz Wetzlar, petrographic microscope, 1908

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This is a Petrographic microscope made in 1908 by E. Leitz Wetzlar. It consists of a microscope body supported by a brass limb. The limb floats on a triangular pillar for fine focus via the top screw. Coarse focus is by rack & pinion. The microscope is supported by a heavy brass base painted with black lacquer. The support is hinged just below the insertion of the rotating stage to allow the instrument to be tilted. The polarizing condenser is centered by a locating pin. It has a leaf iris for contrast control. Inside the condenser is the single Nicol prism polarizer. Sample illumination is provided by the substage mirror. The microscope body consists of two tubes: the draw tube and body tube. The top, draw tube is calibrated for 170-190mm optical tube length objectives. The body tube has several slots and cutouts to allow placement of PLM-specific components: an Amici-Bertrand lens (for observation of interference fringes), a Tube Analyzer (upper Nicol), and a compensator slider. The objective is held in place by a spring-loaded quick release mechanism: the objective clutch. The objective mount has two screws to center the objective. The eyepiece is a Huygenian type, but with a focusing mechanism for a crosshair or reticle.

References: Golub Collection #213