Brass Equinoctial Ring Dial by Richard Rust, signed R. Rust, callibrated in individual degrees 0-90-0 through two quadrants on both sides of the meridian ring, the hour ring engraved I-XII-I with vertical divisions extending to the inner rim, with sliding pinhole cursor on bridge engraved with the initials of each month on one side, a declination scale 20-0-20 and the Zodiacal sigils on the other, on sliding cursor (lacking suspension ring), dia. 5 in.
Provenance: Family descent from the vendor's grandfather.
Note: Richard Rust is listed as an inventor and maker of mathematical instruments at The Minories, London, from 1753 - 1778, and then at various addresses until 1781. He was an apprentice of John Parminter and later a partner with John Adams. For an English ring dial of similar design (by George Adams), see Skinner's sale of Mechanical Music, Science & Technology, 4 May 2005, lot 1245. For an illustration of this lot, please see the webiste: www.skinnerinc.com