Parkinson & Frodsham, Change Alley, London, Movement No. 743, 57 mm, 171 g, circa 1822

A heavy pocket chronometer with spring detent escapement
Case: silver, tiered, polished, consular case, case maker's punch mark "CL" (Charles Lupton, 6 St. James's Place, Clerkenwell). Dial: enamel, radial Roman hours, auxiliary seconds, signed, gold spade hands. Movm.: full plate movement, frosted, gilt, signed, keywind, chain/fusee, bimetallic chronometer balance with 4 screws and 2 movable trapezoid weights, freesprung blued helical balance spring, chatoned diamond endstone on balance.