08-004. English, mid 19th century, signed in script "A. Yeates, London". Made of polished lacquered
brass, the semi-circular protractor is 6 1/2" diameter, with a vernier reading out to 1 arcmin. At
the center of the circle is a window with a engraved crossbar to indicate the center. The arm
extends 5 3/8" beyond the circle, with a pair of small folding sight vanes 5" apart. On the bottom
side of the protractor there are 2 pins to hold it in place on the paper. Also included in the case
is a pair of ivory "targets" with ruled lines for use with the sights, an extra pair of screws with
pins, and a large thumb tack. This very unusual sighting protractor is in fine overall condition,
with all of its original lacquer finish. The original 13 1/2" x 5 7/8" x 1 3/8" fitted mahogany
case, is in very good overall condition, except that the top is a bit warped. Andrew Yeates was an
optical/mathematical/astronomical instrument maker working in London from 1840-1863, but few of his
fine instruments are known in collections. He is known to have been interested in precision
instruments used in survey work, but we can find no other similar example of a sighting protractor
such as this one to help determine its original purpose.
