Chronometer, marine chronometer, a two day marine chronometer by Charles Frodsham with Earnshaw escapement and bimetallic balance, the movement is fitted in a brass bound 3 tier mahogany box with flush fitting handles, signed on the dial Charles Frodsha

Chronometer, marine chronometer, a two day marine chronometer by Charles Frodsham with Earnshaw escapement and bimetallic balance, the movement is fitted in a brass bound 3 tier mahogany box with flush fitting handles, signed on the dial Charles Frodsham, 7 Pavement, Finsbury Square, London, No 1471 c. 1830.
A marine chronometer is a timepiece that is precise and accurate enough to be used as a portable time standard; it can therefore be used to determine longitude by means of celestial navigation.