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Microscope

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made in London

Microscope
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This simple brass microscope in a fitted wooden case was made in London around 1830. In an effort to improve the optical characteristics of the simple microscope in the early 19th century, David Brewster (1781-1868) suggested that single lenses might be made from materials with a very high refractive index, such as diamond or sapphire, which would lesser the effects of spherical aberration, a fuzziness of the image caused by the spherical curvature of glass lenses. A few of these were made, but they were expensive to produce and difficult to manufacture.

The microscope was possibly designed for jewel lenses, although these are not present. It is signed on the stage 'Britton / Barnstaple'. A folding tripod base unscrews and is reversed and screwed on to the base of the pillar, at the top of which is a compass joint to move the limb, holding the mirror at the bottom (lacks glass) and the simple stage at the top. The eyepiece is moved on a triangular-sectioned pillar by rack-and-pinion, acting as coarse focussing. It has three objectives: 1/4, 1/2 and 1 inch simple objectives.

The design of this microscope signed by William Britton of Barnstaple is illustrated by Brewster in his Treatise on the Microscope (Edinburgh, 1837), where it is described as the pre-eminent London microscope manufacturer, Andrew Pitchard's, stand for sapphire glasses: however, all the objectives are made of glass. Pritchard's co-worker on jewel lenses, C.R. Goring, retired to Devon some time before his death in 1840, which may explain the signature on this instrument.

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