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A circular ivory quadrant for latitude 51o 32', probably by John Browne, signed with the initials JB

Currency:GBP Category:Everything Else / Other Start Price:NA Estimated At:5,000.00 - 7,000.00 GBP
A circular ivory quadrant for latitude 51o 32', probably by John Browne, signed with the initials JB
A circular ivory quadrant for latitude 51o 32', probably by John Browne, signed with the initials JB and Londini fecit, the instrument engraved on one side with a heart-shaped cartouche which contains on the left a Gunter-type quadrant and on the right a table of stars names and positions. Outside the quadrant is a degree scale marked Shadowes and Degrees, both arcs are radial from a small hole on the opposite side which is also centre of the quadrant. Also fixed to this side are two brass sights, which may be later additions. The second side of the instrument is engraved with a series of concentric scales including calendars, the Sun's declination and the Sun's position in the zodiac. An index for facilitation the reading of these dials is pivoted from the centre, English, circa 1660,
diameter 12.7cm, thickness 0.8cm.
A very similar, but smaller ivory quadrant was sold at Sothebys in 2001. Also ascribed to John Browne, this instrument is similar in design to an instrument in boxwood signed 'J B Londini fecit' in the National Marityime Museum, Greenwich and two other instruments in ivory in the British Museum.
John Browne (fl.1648-post 1697) was Master of the Clockmakers Company in 1681 and seems to have specialised in instruments made of wood or ivory. Between 1661 and 1668 he published four books on rules, two of them being issued in association with Henry Sutton, including The Description and use of the Carpenter's Rule.. to which is added the Use of a (portable) Geometric Sun-Dial, with a nocturnal on the backside, London, 1662.
See also Gloria Clifton, Dictionary of British Scientific Instrument Makers 1550-1851, London, 1995.
(see illustration)
£5,000-7,000