Lot Essay
The Course-correcting instrument was used for comparing a compass indication against a visual observation. The original patent was taken out on 27th January 1872, No 265, by J. Middleton.
Details
A rare example of a Course-correcting instrument by John Middleton, circa 1872
the compass-divided pewter dial set within a brass octagonal gimball with folding sight with centre thread stamped either side WESTERLY VARIATIONS EASTERLY VARIATIONS and with a brass plate stamped SHIPS HEAD secured to case behind, stabilised by a cast brass hub painted black with embossed Royal Arms and BY H.M.S. ROYAL LETTERS PATENT, secured by sylised brass nut to thread leading to gimball weight underneath and tall centre sight with centre thread above, the external brass plate embossed Middleton & Cos Hartlepool Patent Polarus & Compass Adjuster, each dial with threaded studs for setting and folding sighting scope secured to outer ring, the whole mounted in a octagonal mahogany case with Clinometer embosed PORT STARBOARD and caliobrated from 0-50 both sides, inset brass handles -- 18 x 16in. (46.5 x 42cm.) together with copies of origianl patent and catalogue
See illustration
the compass-divided pewter dial set within a brass octagonal gimball with folding sight with centre thread stamped either side WESTERLY VARIATIONS EASTERLY VARIATIONS and with a brass plate stamped SHIPS HEAD secured to case behind, stabilised by a cast brass hub painted black with embossed Royal Arms and BY H.M.S. ROYAL LETTERS PATENT, secured by sylised brass nut to thread leading to gimball weight underneath and tall centre sight with centre thread above, the external brass plate embossed Middleton & Cos Hartlepool Patent Polarus & Compass Adjuster, each dial with threaded studs for setting and folding sighting scope secured to outer ring, the whole mounted in a octagonal mahogany case with Clinometer embosed PORT STARBOARD and caliobrated from 0-50 both sides, inset brass handles -- 18 x 16in. (46.5 x 42cm.) together with copies of origianl patent and catalogue
See illustration