Lot 523: WARD, William (fl. 1735) and Caleb SMITH (1723-1762). The Description and use of a new Astronomical Instrument, for taking Altitudes of the Sun and Stars at Sea, without an Horizon together with an Easy and Sure Method of observing the eclipse

WARD, William (fl. 1735) and Caleb SMITH (1723-1762). The Description and use of a new Astronomical Instrument, for taking Altitudes of the Sun and Stars at Sea, without an Horizon together with an Easy and Sure Method of observing the eclipse of Jupiter's Satellites, or any other Phoenomenon of the like Kind, on ship-board. London: for G. Strahan et al, 1735. 4 o (247 x 188 mm). One engraved folding plate (light dampstaining and tiny hole to blank margin). (Some minor chipping to a few corners). Modern marbled boards. FIRST EDITION. A rare work addressed to the commissioners appointed by Act of Parliament, for the Discovery of the Longitude at Sea. Ward and Smith claimed to have found "an easy and sure Method of ascertaining the Longitude, or Difference of Meridians at Sea, within a Degree of a Great Circle or sixty Geographical Miles, by the means of certain Instruments contrived for that Purpose." The longitude prize was offered by the British government through an Act of Parliament in 1714 for the precise determination of a ship's longitude and was finally awarded to Harrison in 1773.