1851 Great Exhibition: Official Catalogue: Class X.: W. Austin Ashe
194. ASHE, W. AUSTIN, 15 Brompton Crescent — Proprietor.
Great circle course indicator, invented by Lieut. E. D. Ashe, of the Royal Navy. Its object is to point out the course which a ship must steer in order to sail on a great circle between any two places on the globe, instead of steering by the true bearings of the port to which she is bound, and thereby materially shortening the voyage, in some instances to the amount of 600 miles.
[It is well known that the shortest line which can be drawn between any two places on the surface of the globe, is the arc of the great circle intercepted between them; great circle sailing, however, cannot always be practised, but it may be usefully combined with other sailings. This instrument is adapted as a companion to Mr. Towson's tables for "Great Circle Sailing," lately published by order of the Lords of the Admiralty.]