A mid 19th Century English chronometer with duo in uno hairspring by Frodsham in a silver open face case. Gilt half plate keywind movement with fusee and chain. Harrison's maintaining power. Plain cock with diamond endstone. Compensation balance with rare freesprung duo in uno blue steel hairspring. Earnshaw type spring detent chronometer escapement, escape and seconds pivots with endstones. Signed and numbered white enamel dial with subsidiary seconds, Roman numerals, blue steel seconds hand, gold hands. Engine turned silver open face case with ribbed middle, maker's mark “TH” in an oval.