surveyor's compass
Date: circa 1850
Inventory Number: 5203a
Classification: Surveyor's Compass
Subject:
Maker: E. & G. W. Blunt (1824 - 1866)
Cultural Region:
Place of Origin:
Dimensions:
20.3 x 36.2 x 16.5 cm (8 x 14 1/4 x 6 1/2 in.)
Accessories: ball-and-socket joint (5203b); tripod (5203c)
Description:
The instrument is made of brass with a silver dial. The two sighting vanes are removable. One is made of two narrow slits, the other of eight small circular apertures (four for the upper and four for the lower slits when looking through the latter). There is a small thumb knob to adjust the lifter arm.
On the South side, on the arm, is a circular universal bubble level. On the North side, an unusual round counter (0-10). The dial's face only has eight cardinal points. Degrees are engraved on the raised divided scale (0-360), divided in half degrees and marked to every ten. It is supported by a heavy ball-and-socket joint and a tripod.
On the South side, on the arm, is a circular universal bubble level. On the North side, an unusual round counter (0-10). The dial's face only has eight cardinal points. Degrees are engraved on the raised divided scale (0-360), divided in half degrees and marked to every ten. It is supported by a heavy ball-and-socket joint and a tripod.
Signedon arm, counter: E & G W Blunt / New York
FunctionThe surveyor's compass is an instrument used in surveying (or in navigation in rare cases) to measure horizontal angles, what is called bearing or azimuth.
For a nice discussion of this intrument, see the following website.
For a nice discussion of this intrument, see the following website.
ProvenanceBelonged to Alexander Johnston, Jr. (1815-1890) of Wiscasset, Maine.
