William A Burt was a noted surveyor of public lands and the inventor of the typewriter and the Burt Solar Compass. William A had two sons who were also surveyors, John and William. In 1852 William Burt engaged a Detroit instrument maker, John Bailey, to produce Burt’s Patent Solar Compasses. During the next year Bailey and William A Burt's sons (John and William) formed Burt & Bailey to produce surveying instruments. Bailey left the firm in 1856.

This is a very special instrument. As far as I can tell, this is the oldest instrument to feature latitude and declination arc adjustment mechanisms that were installed when new. Numerous pre-1854 Young Solar Compasses have tangent screws for adjusting the arcs, but these were all retrofitted after 1854 as instruments came back to Young for adjustment and retrofitting. According to Bob Miller's Book on Burt's Solar Compasses, Young started adding tangent screws to the arcs around 1866. Gurley did not start producing solar compasses until 1858. And it's not surprising that a Burt family made instrument featured an important evolution in the Burt Solar Compass design before other makers.

The gear & pinion arc adjustment system is also unique. Tangent screws quickly became the preferred way (the only way, actually) of adjusting the arcs. This is the ONLY known instrument with a functioning rack & pinion system, and the system works great. The 1858 Gurley solar compass I sold in 2019 is the only other known instrument showing the existence of a gear & pinion arc adjustment system.

As the pictures indicate, this is a REALLY nice instrument.

This instrument MIGHT be missing the Sight Pin in the center of the instrument. That sight pin is in every other solar compass I have seen. If you study the pics below, however, you will see pin holding nuts to the immediate right of both verniers. Those pin holding juts are 180 degrees from each other. I think Burt used those pin holding nuts to create a more accurate way to sight a reference point than using the Sight Pin in the center of the instrument.

This is truly an outstanding and rare instrument - one of the few known that was made by William A Burt's family - and has multiple novel design features. Please contact me with many questions.