Marine Chronometer by John Poole
A Fine Two Day Marine Chronometer by John Poole, London. No.1064 c.1846
Three tier mahogany brass bound box with inset carrying handles, decorated brass escutcheon and key to the base, ‘push button’ brass knob opening to the third tier. Brass plaque to the front of the box carrying the number 1064. The mahogany box has a rich patina with signs of age that one would expect to find on an instrument of this age.
The movement is a full brass plate chain fusee with four ringed pillars and ten jewels with Harrison’s maintaining power. Earnshaw type spring detent escapement with split bi-metallic balance with wedge shaped temperature compensation weights. Blued steel helical balance spring and faltered diamond endstone. The 3 ¾ inch dial signed ‘Poole, London’ and numbered 1064 within the seconds ring, with Roman numerals, original brass hands and subsidiary dials for up/down (state of wind) and seconds.
The movement is set in a lacquered brass bowl with screw down bezel mounted within a pivoted gimbal with knurled locking screw and tipsy key.
All the wheelwork and parts of this chronometer are original and in good condition, the movement (in line with all clocks offered for sale by Olde Time) has been stripped down, completely overhauled, cleaned and tested.
John Poole became one of the great chronometer makers of the world, his movements and ideas were used by many other makers. It is well documented that one of his most important inventions was his own auxillary compensation (later to become known as ‘Poole’s auxillary compensation’) a device to correct low temperature error. He won the famous Grenwich trials (which were conducted by the Admiralty through the Royal observatory at Grenwich) twice, once in 1844 and again in 1854 for achieving the highest rate of accuracy. Sadly, John Poole took his own life shortly after winning the gold medal for excellence at the Paris exhibition. His business was carried on by his brother James.
John Poole was an outstanding chronometer maker, one of the very best he was established c.1840, this particular example was one of his earlier chronometers, he developed his auxillary temperature compensation c. 1850. C.1846
Source: Tony Mercer’s informative book: Chronometer makers of the world.