Gurley started making solar compasses in 1858, and thereafter quickly dominated the market for solar instruments until the early 20th century. The instrument offered here was one of the very first solar compasses made by Gurley, and is the only known Gurley solar compass to reflect a critical design decision made by Gurley immediately after Gurley decided to start making solar compasses.

The original Burt Solar Compass as produced by William Young required the surveyor to make fine adjustments to the latitude and declination arcs of the solar apparatus by hand. (Click here for solar compass nomenclature). This is one of the only weak points in Burt's original design. The Burt family itself designed a rack & pinion solution to this problem circa 1854 - see the Burt & Bailey Solar Compass offered here. This rack & pinion system apparently predates any tangent screw solution to the problem.

Gurley's 1958 Manual contains the first illustration of its 1858 Solar Compass - the illustrations shows a small tangent screw adjustment for the declination arc and a rack & pinion adjustment for the latitude arc (click here or on the pic for a blow up of the illustration):

Gurley quickly discarded the rack & pinion system for a tangent screw approach. The Gurley solar compass offered here is the ONLY known Gurley solar compass showing Gurley's FIRST 1858 Design.

Starting in 1858, Gurley assigned a key employee, George Raymond, to focus on making solar compasses. Mr. Raymond held that spot for decades, and engraved his name in many of the solar compasses he helped make, and dated the signature. The internals of this solar compass contained George Raymond's signature, along with a date June 1858, confirming that this solar compass is indeed the original 1858 Gurley design.

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