FRANKLIN SEARCH -- Royal Observatory Pocket Chronometer in mahogany box, no. 4136 by French, Royal Exchange, London, ca. 1835.
A silver-cased pocket chronometer with Earnshaw spring detent escapement, white enamel dial signed and numbered "French Royal Exchange London 4136", the gilt fusee movement similarly signed, cut bi-metallic balance with circular heat compensation weights and helical balance spring., origianl fitted mahogany deck watch box with sliding cover to top inset with bone disc inscribed "French 4136", and with lock to side of case (at III), case hall marked, mahogany box 12.2 x 9.2 x 5.2cm.
An historically important 19th-century Royal Observatory Pocket Chronometer, which accompanied Capt. James Ross in his search of the Arctic for Capt. John Franklin, and later used by Capt. Anderson for the North American Boundary Commission, and Capt. Maxwell for surveying Newfoundland, among other voyages. After 3 previous voyages from 1838 to 1847, French's pocket chronometer was assigned to H.M. Investigator on the first search for Franklin in 1848-49. On returning from the Arctic, where it had been subjected to extremes of heat and cold, it was analyzed in comparison with other chronometers on the expedition, and specifically with a new chronometer by Dent which claimed to be particularly suited to such purposes, French 4136 was deemed to be "decidedly superior" (Report of the Hydrographer, 27 Feb. 1850). After several other expeditions, it then was assigned to Capt. Anderson's North American Boundary survey from 1872 to 1876. The importance of establishing of the northern international boundary between the United States and the then recently created Dominion of Canada was such that great care was taken in choosing "the best portable instruments", overseen by the Astronomer Royal. Sparked by the need to determine whether a trading post of the Hudson's Bay Company for furs hunted by the Chippeway Indians lay in U.S. or British territory, the expedition surveyed 900 miles from the north-west corner of the Lake of the Woods to the summit of the Rocky Mountains. Extreme conditions were endured by the instruments, as well as the men, and Anderson recounted in his report how the men had to use extreme caution when handling the instruments in such cold conditions, lest their hands would freeze to the metal. French 4136 also accompanied surveys of the coasts of Ireland under R. Hoskyn (1857-59), of the West Indies (1861-1866), in the Mediterranean, principally of the coast of Sicily in the Hydra (1867-1868), of Newfoundland in the Gulnare (1882-1886), and of the east coast of Africa in the Stork (1891-93). In addition, it was issued to the Soar Eclipse Expeditions in 1870-71 and 1905. It remained in service to the Royal Observatory until 13 March 1907.