Two-Day Marine Chronometer" Litherland Davies Co

"Two-Day Marine Chronometer" Litherland Davies Co. , Liverpool, No. 1311/ 21616, Hartnup's balance No. 2. Made circa 1870. Fine, two-day marine chronometer with power reserve indication, Hartnup's continuous auxiliary compensation balance and ratchet key. Three-tier mahogany box with external brass handles, glazed upper section with hinged lid (heavily restored). Brass bowl and gimballed suspension. Silvered with Roman numerals, outer minute track and Arabic five minute numerals, subsidiary seconds and Up-and-Down scale. Blued steel "pear " hands. Notes The dial side of the pillar plate is stamped T & JH who were the movement suppliers. The layout and design of the movement with the foot of the balance not inset form the edge of the plate is a typical feature of a movement made in Prescot or certainly Lancashire. The Hartnup Balance John Hartnup, the inventor of the continuous auxilliary compensation balance was Superintendant of the Liverpool Observatory and during the course of his work would have tested many chronometers. This made him acutely aware of the middle temperature error. In an attempt to solve the problem he designed his balance in about 1847 assisted by William Shepherd, a Liverpool chronometer maker. Hartnup did not patent his balance and publicised it widely starting in 1849 in the June issue of "Monthly Notices of the Royal Astronomical Society". Whilst the Hartnup balance works well, it was a difficult and expensive balance to produce and suffe Read more…