178 Mr. G. F. Hutton on Chronometers. 



fectioii, still we appear to have made scarcely any progress to 

 that end during a period ofupwai'ds of twenty years. 



In 1801-2, Mr. Earnshaw deposited two chronometers at 

 the Royal Observatory at Greenwich, which, on trial, were 

 pronounced to be scarcely affected even when the thermome- 

 ter was at 28° of Fahrenheit. For the rate and true per- 

 formance of these chronometers, the Honourable Board of 

 Longitude awarded to that artist the sum of 3000/. 



With the view of attaining to as much perfection in these 

 invaluable instruments as possible, the Right Honourable the 

 Lords Commissioners of the Admiralty, in the latter part of 

 tlie year 1820, " for the purpose of further encouraging the 

 improvement of chi'onometers," were pleased to publish a no- 

 tice in the Gazette, that a depot would be established at the 

 Royal Observatory at Greenwich, where chronometers would 

 be received from their respective makers for a year's trial ; and 

 that, at the end of that period, their Lordships would purchase 

 the chronometer which should have kept the best rate at the 

 price of 300/., and the second best at 200/. ; provided that 

 more than ten chronometers should have been submitted to 

 competition, and that such chronometer should have kept its 

 rate within specific limits. 



In consequence of this notification, upwards of thirty chro- 

 nometers were sent — some by respectable watchmakers, and 

 others by practical artists. During the period, however, al- 

 lotted for the proof of their respective rates, nearly one half of 

 them were withdrawn from the trial. From the rates published, 

 it appears that some of these chronometers varied 20' and even 

 40" per day on their previous rates; and of the remainder, five 

 only seemed likely to attach credit to their respective makers. 



These, indeed, went satisfactorily while the thermometer 

 stood at a moderate temperature; but when, from the short 

 frost at the end of December, it fell to 31° Fahr., their daily 

 rate was affected, some to 10", and others even to 23", in one 

 day. The variation was considerably greater during the suc- 

 ceeding intense frost in .January, when the thermometer fell to 

 27°. The whole exhibited great changes ; and one of them 

 was altered in its rate to nearly 50" in the day: thus, conse- 

 quently, becoming totally useless for the immediate objects for 

 which they were designed — that of attaining pex'fection for astro- 

 nomical and nautical purposes. 



That so great a failure should cause serious disappointment 

 to the Honourable Board, as well as to the scientific world, 

 and to all others interested in their perfection, is not to be won- 

 dered at. And we may fairly presume, that as these five chro- 

 nometers, together with one previously withdrawn, were made 



