A good mid 19th century two-day brass bound mahogany marine chronometer with unusual auxiliary compensationFrodsham, Gracechurch Street London Number 499The three part case with blank brass cartouche inlaid on the top lid, the centre section with 12 point brass star button above a missing number plaque, the lower section with larger 12 point brass star escutcheon and folding handles. The 3.25 inch silvered Roman dial with observatory style seconds dial numbered 499 and signed Two Day's Chronometer. Frodsham Gracechurch Street London below the gold spade hands. The full plate movement with four ringed pillars and maintaining power to the chain fusee, free sprung blued steel helical balance spring with diamond endstone and Earnshaw type escapement, cut and compensated bimetallic balance with unusual auxiliary compensation, sitting in a weighted gimballed bowl. Ticking with a Tipsy key and a case key. 17cms (6.5ins) wide.Footnotes:Purchased 7 October 2002 from Vernon Morris.