A RARE ENGLISH MAHOGANY ANGLE BAROMETER. WHITHEHURST DERBY, DATED 1772 Engraved sivered scale signed WHITEHURST DERBY 1772, vernier with brass adjusting nob, case veneered with well figured mahogany of rich colour surmounted by a gadrooned finial and hemispherical cistern cover. The angle barometer was invented in 1688 by Samual Moorland. Because of the horizontal principle, the scale could be made larger. This barometer is one of only a dozen known dated angle barometers by John Whitehurst and enhances the scale seven times.Their value and deviating shape may have contributed to the fact that they were never made in great numbers. John Whitehurst was a very accomplished clock- and instrumentmaker and worked with reknown scientists as Erasmus Darwin, Josiah Wedgewood, James Watt and the later American president Benjamin Franklin