W&S Jones Lucernal Microscope (No. 113)

Age: 1780–1790
Made by: William and Samuel Jones
Made in: London, England
W&S Jones
30 Holborn London

The Lucernal microscope was invented by George Adams senior (1708–1773), and is described by his son, George Adams the younger (1750–1795) in Essays on the Microscope, etc., London 1787 (p65). Adams claimed that it was of special value in assisting the preparation of a drawing. Comparing the upright compound microscope to his new lucernal microscope he wrote: "I have, however, so improved and altered it, both in construction and form, as to render it altogether a different instrument."

This microscope in the Golub collection is a descendent of the horizontal design first used by the Italian microscopist, Filippo Bonanni, in the latter part of the 17th Century. Lucernal microscopes varied from rectangular boxes (an early Adams design), to brass cylinders, (e.g., Microscope No. 37) to the pyramidal design of this microscope in the Golub Collection. After the death of Adams the younger in 1795 the family business was carried on by William and Samuel Jones, and it is they who made this particular instrument. The stage is engraved W&S Jones, 30 Holborn London.

The lucernal microscope is basically an optical bench supported by a brass three-leg pillar. The main body of the microscope is a pyramidal-shaped mahogany box that is bolted to the stand via two brass pillars to a rectangular wooden rail. The stage is supported by an additional pillar and can be moved in two axes using a long actuator rod. A condenser lens serves to focus light onto the slide, which is magnified by the objective and projected to the user through a very large projection lens system. In order to use the microscope the observer would position their eye along the optic axis. Given the large size and focal length of the microscope eyepiece lens, this position is located by means of a "shade" with a target hole (shown above extending right from the instrument). When the eye is correctly placed the entire eyepiece lens is illuminated, and the magnified specimen is visualized. The illuminating system was usually an oil lamp. Some specimens are held in place on the specimen holder by a brass frame and spring mechanism, other specimens were placed directly onto the stage and held in place with the stage clips. Focusing is accomplished by turning a thumbscrew (at the observer's end) that positions the specimen holder at the objective end. Two rack and pinion mechanisms change X and Z position of the specimen. The observer used long handles to turn these pinions.

There are eight objectives plus a Lieberkuhn reflecting lens with this instrument. A drawer in the bottom of the case (case is now missing) held accessories: stage forceps/pointer, 17 opaque specimen slides, two bone specimen slides, three wooden specimen slides, and a small bone cylinder for storing circular mica coverslips and brass retaining rings.

Imaging is poor at best, due mainly to poor illumination.

The microscope system is approximately 35w x 65d x 65cm tall.

Featured 04/2016

Fri, May 6, 2016