a 1-day marine chronometer movement now mounted vertically in a box with carrying handle. Made in 1796, this chronometer, serial number 427, was used in the Royal Navy until 1830. It was subsequently transferred from the Admiralty to the Royal Observatory Greenwich. It was then adapted and fitted with a handle, for use in carrying accurate time around the Observatory to compare the rates of various astronomical regulators against the standard clock. Full-plate movement, Peto's cross detent with Earnshaw escapement. Large three-armed balance, oversprung with blue helical spring.