signed on ivory plaque MADE BY JOHN DOBSON 1730 FOR MR THOMAS SALKELD, with lignum vitae frame, boxwood arcs and replaced vanes, the 30 degree transversal scale with fleur de lys stamped decoration, the back with scales for the Sun's declination and the right ascension, 22 in (56cm) long, The 1°- 62° scale has a Type A style of the 650 arc: no outer scale for correcting the sun’s semi-diameter, as is found in 32% of instruments examined by N. De Hilster. This type was only found in European instruments up to 1740