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Gregorian Reflecting Telescope with Stand, English, c. 1710

Inventory Number: 20020
Object Type:
Persons: Joseph Jackson
Date Created:
Place Created: England United Kingdom Europe
Accession Number: 1925-43
Brief Description: English Gregorian reflecting telescope of brass with a
weighted wooden stand. The tube of the telescope was originally covered with fish-skin, but this has decayed. Unsigned and undated, but c.1710 likely.

This is probably the oldest surviving example of the reflecting telescope invented, in 1661, by James Gregory (1638-75), described in his Optica Promota, 1663. In the Gregorian telescope the eye-piece is directly behind a concave mirror, which has a hole in the centre. Through this hole the image is reflected by a small adjustable concave mirror at the further end of the tube. This instrument has an aperture of 2'. It is focussed by turning the threaded rod at the side of the tube.

As originally sold these instruments were accompanied by a small hand-augur for boring a hole in the side of a post or tree, into which the mounting could be screwed, when the telescope was "used abroad".
Primary Inscriptions:
Provenance: Lent by Christ Church, Oxford in 1925.
Collection Group: Orrery Collection
Dimensions:
Height Width Depth Diameter Unit
520 mm

Narratives

Image with multimedia irn 24250Image with multimedia irn 24248

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