Author: Walker, Ralph
Title: A Treatise on Magnetism, with a Description and Explanation of a Meridional and Azimuth Compass, for Ascertaining the Quantity of Variation, Without any Calculation Whatever, at any Time of the Day.
Place Published: London
Publisher:Printed by R. Hindmarsh
Date Published: 1794
226,  pp. Seven engraved folding plates. (8vo) 21.5x13 cm (8½x5¼ ") old half calf and marbled boards. First Edition.
Ralph Walker (1749-1824) was a Scottish-born civil engineer, particularly associated with harbor engineering works in London. He travelled to the Caribbean and managed estates in Jamaica belonging to his mother's family before returning to settle in London in 1793 and becoming involved in plans for London's wet docks. The present work discusses the causes for variation of compasses at sea. Well represented in institutional collections but scarce in the trade, no copies at auction since 1981.