Marine Chronometer John Poole, London, # 4942
Added: -0.3-.2023

This stuff was recently sold.

Marine Chronometer John Poole, London, # 4942
Circa 1880
the silvered and engraved dial signed John Poole, MAKER TO THE ADMIRALTY,
57, Fenchurch St. London. 4942; and further engraved “The Gold Medal
Paris 1867”, with subsidiary dials for seconds and up/down dials with blued
steel hands, gold hands, the movement marked 4942 with spotted plates,
chain fusee, Earnshaw-type spring detent escapement, cut bimetallic balance
with circular heat compensation weights and Poole’s auxilliary. In a three
tiered mahogany box with a brass gimbal, bowl numbered 4942, and handles
to the sides, a vacant bone plaque, with double-ended brass tipsy winding
key, and a case key.
According to Tony Mercer (Chronometer Makers of the World), John Poole
’became one of the great chronometer makers, his movements and ideas used 
by many others’. One of his most important inventions, which features in 
this instrument, was ’Pooles Auxilary Compensation’, a device to correct
low temperature error. He won the Greenwich trials twice in 1844 and 1854
achieving the highest accuracy rates of the day.
John Poole took his own life in 1867, shortly after winning the gold medal
at the Paris Exhibition, his business was carried on by his brother James
who’s numbering system has still to be resolved. This instrument is
still signed ’John Poole’ at Fenchurch St. and must be before the firm 
moved in 1870, indicating that it probably dates from shortly after John’s
death.
The chronometer in a perfect condition, holds time well