Advertisement for T. Cotterell & Co., Chronometer Makers, announcing an award granted by the Board of Admiralty to Cotterell for its performance at the Public Trials, Royal Observatory, Greenwich

London, 1822. The advertisement for the London chronometer makers reads: "The Honorable Board of Admiralty Awarded T. Cotterell & Co. a Prize of 200 Pounds for the Extraordinary Accuracy of the Performance of their Chronometer, the actual Variation on its Rate in 12 Months being only 70 Hundredth Parts of a Second". It goes on to say that the Admiralty purchased several of the chronometers "for their superior performance on the Public Trials at the Royal Observatory, Greenwich. ... Cotterell have also been liberally encouraged by the Swedish Government, And by many Scientific Navigators". Chronometers at the time played a critical role in navigation at sea, having been recently introduced as the best method to determine exact longitude. Chronometers made by Kendall were used as early as the 1770's in Captain Cook's expeditions; and by Capt. John Ross in expeditions to the Arctic. Another Kendall chronometer was used by Lieutenant Matthew Flinders in expedition to Australia in 1801. The Public Trials referred to in this advertisement commenced in 1820. By 1850 reliable and inexpensive marine chronometers were widely available and replaced the lunar distance method of measuring longitude. 5 3/4 x 5 1/2". Text in black on white paper; paper toned, edges slightly ruffled, o/w very good.