Stephen Bithray Compound Microscope (No. 93 )

Age: c1826
Made by: Stephen Bithray
Made in: England
Bithray, Royal Exchange, London

This is a brass, Gould-style compound microscope made c1826 by the instrument maker Stephen Bithray of London. In the early 19th Century Bithray was noted for his surveying instruments such as barometers, telescopes, sundials, and sextants. He made these instruments at his shop at 4 N Piazza in the Exchange from 1826–1838. After the Exchange was damaged by fire Bithray moved to Finch lane during its reconstruction, then back to 29 Royal Exchange from 1840 to c1860. This microscope is probably an early Bithray model from his Piazza location.

The microscope is typical of the Gould-style with its tapered body tube and objective mounted on the end of a support arm. It is similar in style to No. 47 in the Golub Collection, but is free-standing on a tripod base. The rectangular support shaft is mounted to a hinge at the top of the round pillar allowing the microscope body to change orientation from vertical to fully horizontal. A rack on the front face of the rectangular support moves the stage for focusing. A bull's eye lens and Lieberkuhn are available to illuminate opaque specimens. The square stage has a separate top specimen holder retained by two pins that slide in channels. The microscope body screws into a horizontal support arm. The arm slides through a slot in the support pillar end cap, and is held in place by a cork friction plug. The objective screws into the bottom threads of the arm. The microscope comes with four single-lens objectives. Two are stamped "1" and "2"; whereas the other two have no marking. A single biconvex field lens is fitted to the top body tube. The eyepiece consists of two biconvex lenses. The microscope comes with a Nicol prism analyzer for polarized light microscopy, although now the polarizer is missing. The single-side convex mirror is mounted to a gimbal attached to the lower part of the rectangular support. Engraved on one leg "Bithray, Royal Exchange, London". The microscope is approximately 27cm tall. Imaging is good, but shows chromatic aberration at high magnification.

Accessories consist of a black/white disc, a circular live box and a live slide. The microscope folds for storage and it, with the accessories, fit within a mahogany case.

Featured 04/2009

Tue, Mar 31, 2009