A rare early 19th Century brass portable equatorial transit telescope, the 6¾inch diameter vertical circle signed on the index arm W. & S. Jones Holborn London, the telescope with rack and pinion focusing, aperture for cross hair illumination, tapered horizontal support, to vertical circle with silvered scale, twin verniers, magnifiers and reflectors, hanging bubble and cross bubble level, on tapered cresent and straight mounts with lateral supports, rectangular horizontal plate, with milled rackwork, on conical horizontal axis supports, to twin A-frame trunnions, with central cylindrical counter balance pillar, the base with engraved silver hour scale divided 1-12(x2), the hours divided 0-20-40-60, the outer circle divided 0°-180°(x2), twin verniers, magnifiers and reflectors, on flat tripod foot with adjustable levelling screws, in fitted triangular shaped mahogany carrying case - 27¼in(69cm)high

Details
A rare early 19th Century brass portable equatorial transit telescope, the 6¾inch diameter vertical circle signed on the index arm W. & S. Jones Holborn London, the telescope with rack and pinion focusing, aperture for cross hair illumination, tapered horizontal support, to vertical circle with silvered scale, twin verniers, magnifiers and reflectors, hanging bubble and cross bubble level, on tapered cresent and straight mounts with lateral supports, rectangular horizontal plate, with milled rackwork, on conical horizontal axis supports, to twin A-frame trunnions, with central cylindrical counter balance pillar, the base with engraved silver hour scale divided 1-12(x2), the hours divided 0-20-40-60, the outer circle divided 0°-180°(x2), twin verniers, magnifiers and reflectors, on flat tripod foot with adjustable levelling screws, in fitted triangular shaped mahogany carrying case - 27¼in(69cm)high
See Back Cover Illustration

Lot Essay

The inclusion of the hour scale possibly indicates that this instrument was used for on-shore observations for checking siderial time.
William Jones a student of Benjamin Martin, also worked with George Adams the Younger. He joined his father John in 1784 in the firm Jones & Son. In 1794 Samuel joined his brother and the company became listed as William & Samuel Jones, working from Holborn Hill until 1802 then to High Holborn, where they remained until 1860. William was heavily influenced by Adams Younger whose copyrights he purchased in 1795. He was subsequently involved in editing the Adams catalogues and refind some of the more complex designs, especially the Adams portable astronomical instruments

Literature
J.A.Bennett The Divided Circle 1987
Nicholas Goodison English Barometers 1680-1860 1985

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