Edmund Brown (1800-about 1867) spent 20 years with Richard Patten in New York, first as an apprentice and then as a journeyman. In 1835, when Patten withdrew from the business, Brown and another employee took over the shop at the Sign of the Compass Card. In 1841, Brown joined with Bush G. Brown, and began trading as E. Brown & Son. This partnership lasted until 1863. This compass dates from that period.
This compass has a variation arc on the north arm that extends 20 degrees either way; the vernier, moved by a tangent screw on the south arm, reads to single minutes. There is a level vial on the south arm. The tangent screw and the decoration of the face (a circle of flowers and leaves) are typical features of New York compasses. The compass has two sets of vertical sights. The plain ones are probably original with the instrument. The others, which are graduated so that vertical angles can be read, are probably not.
One label in the box reads "E. BROWN & SON, MATHEMATICAL INSTRUMENT MAKERS No. 27 Fulton Slip NEW YORK." The other label is that of Wm. J. Young & Sons of Philadelphia, a firm that may have repaired the compass and supplied the graduated sights.
Ref: Charles E. Smart, The Makers of Surveying Instruments in America Since 1700 (Troy, N.Y., 1962), pp. 16-20.