Good morning Bill, The compass is a Burt Astronomical Compass invented by William Austin Burt in 1855 or thereabouts.
Burt described its function and use in some detail. Burt, William A. (1881) A key to the solar compass, and surveyor's companion; comprising all the rules necessary for use in the field. Also, description of the linear surveys, and public land system of the United States; notes on the barometer, suggestions for an outfit for a survey of four months, etc., etc. New York, D. Van Nostrand. 5th edition. (Facsimile reprint by Carben Surveying Reprints) There is also some more information in his biography Burt, John S. 1985 They left their mark. William Austin Burt and his sons, surveyors of the public domain. Landmark Enterprises, Rancho Cordova. The "Key to the solar compass" is available as a free download from Internet Archive (a wonderful source of all sorts of old books and journals). Different editions are at the following URLs http://www.archive.org/details/keytosolarcompas00burtrich http://www.archive.org/details/akeytosolarcomp00burtgoog http://www.archive.org/details/akeytosolarcomp01burtgoog Cheers, John John Pickard john.pick...@bigpond.com In cold, overcast and rainy Sydney. Where has spring gone? ----- Original Message ----- From: Bill Gottesman To: Sundial Mailing List Sent: Thursday, November 04, 2010 1:04 PM Subject: Mechanically Complex Solar Compass on sale at auction I saw (on-line) this interesting sun compass for sale by auction this coming November 20th. I have not seen anything like it. Other scientific instruments, clocks, sundials for sale at same auction. I doubt I will bid on it. -Bill http://www.skinnerinc.com/asp/fullcatalogue.asp?salelot=2527M++++363+&refno=++874110 Lot 363 Brass Solar Compass by W. & L. E. Gurley, Troy, New York, the brass instrument with Burt's solar attachment, horizontal circle read by opposing verniers, blued steel needle and scale calibrated 0-15 in two segments and engraved W. & L. E. Gurley, Troy, NY, silvered vertical half circle arc graduated to 30 minutes with vernier scale and sighting mounts, silvered declination and hour calibrated arcs, dual spirit levels, graduated sighting vanes and thumb screw leveling tripod attachment, ht. 14 in. Estimate $2,000-4,000 ------------------------------------------------------------------------------ --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
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