Reflecting telescope

This reflecting brass telescope was made in London around 1760. It is signed on the mirror retention plate 'JAMES SHORT LONDON 180/1098 = 18.' The coding on Short's instruments establishes their date and place in his sequence. This one has a nominal focal length of 18 inches; it was the 180th he had made of that focal length; and it was the 1098th telescope that he had made.

The 18-inch focus mounted Gregorian reflecting telescope lacks its mirrors and lenses. It has an external focussing rod, and a telescopic sight. It is pillar-mounted on a folding table tripod stand, and is adjustable in the vertical plane by a tangent screw.

There was a long tradition in the making of reflecting telescopes, both for the dilettante market as well as for the more serious scientist, and the finest instruments during the 18th century were produced in London. The quality of optical glass at this period meant that the image seen through the refracting image remained comparatively poor at high magnifications. James Short (1710-68), the renowned telescope maker, made only reflecting telescopes, and in fact his skill lay in the polishing of metal specula (mirrors) of these instruments. James Short's skills in polishing metal specula, ground to the correct curvature to provide an erect image, without chromatic aberration, was largely self-taught. He left Edinburgh in 1738 for London, where the quality of his work rapidly established an international reputation for him.

Record details

To search on related items, click any linked text below.