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MACKAY, Andrew.

The Theory and Practice of Finding the Longitude at Sea or Land:

to which are added, various methods of determining the latitude of a place, and variation of the compass; with new tables.

Stock Code
London, for J. Sewell, P. Elmsly, and J. Evans, 1793

First edition of this important and scarce work on Longitude. The Scottish teacher of navigation, Andrew Mackay (1758-1809), 'corrected the latitude of Aberdeen, estimated the longitude by comparing timings of Jovian satellite phenomena with Greenwich, and rated chronometers. Meantime he earned his living teaching mathematics, geography, navigation with lunars, surveying, and fortification' (ODNB) and the current work gained him the 'thanks of the boards of longitude of England and France' (ibid.). In his Preface, Mackay makes an interesting reference to the horologists John Harrison, Larcum Kendal and John Arnold 'If a chronometer or timekeeper could be constructed, so as to go uniformly when placed in different position, and under different degrees of heat, then would this method of finding the longitude at sea be a most valuable acquisition to the navigator... every person acquainted with the principles of watchmaking must highly admire the accuracy of Harrison's timekeeper. Those made by

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First edition, 2 volumes bound as one, 8vo (21.1 x 12.6 cm). 7 engraved folding plates. Recent half calf period style (retaining the original endpapers), red morocco label, marbled sides. Scattered foxing and a few old pale stains. A very good copy, with half-title to both volumes.


Adams & Waters (English Maritime Books Printed Before 1801), p. 407.

Stock ID:96140

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