EXPERIMENTS ON CHRONOMETERS. 47 



of accuracy. Indeed Mr. Cuminirig, in his treatife on clock 

 and watch work, has fuppofed that the influence of the oil 

 may be in forae cafes even beneficial to the performance 

 of the machine ; though it muft be allowed he there fpeaks of 

 fuch as have no provifion againft the effefts of heat and cold. 

 And though Mr. Mudge in fomeof his letters to his Excellency 

 the Count de Bruhl does write, that when the air was moid 

 in Devonfliire (where he made and tried his machines) they 

 retarded their rates ; yet the quantity of error produced by 

 this fuppofed caufe was fo fmall, that it gave him no unealinefs 

 with regard to their fate. But the very different performance of 

 machines on the fam^ conftrudion, ftrongly induce me to be- 

 lieve that mofl: of the errors hitherto found in the befl time- 

 keepers have been produced by latent mechanical cau fes 

 coexiftent with the machines, or rather, with the times they 

 were lirft put in motion. 



Various opinions have been entertained by gentlemen of Opinions re- 

 fcientific and mechanical acquirements, and by artifts "poii caufis"^f 'n- e ■ 

 this fabjecf. One in particular has very generally prevailed, laiities, Varia- 

 namely, that the errors have arifen from inequality of power ''?".'" ^^^'"^'"' 



•' . taming power, 



derived from the main fpring, and the train of wheels. That inconfiderable. 

 very great errors will be produced by thefe caufes, (if not re- 

 moved by good workmanfhip,) muft on all Iiands be admitted ; 

 but where the execution has been correct, the errors will be 

 trifling indeed, and mufl always remain nearly the fame. 

 The late Mr. Arnold, on being allied by a Committee of theRemontoirecon- 

 Houfe of Commons his opinion of the Remontoire, faid, that '^^""'5!* ^^ 



1111 Arnold^ 



it was only a help to bad workmanflisp. 



Mr. Harrifon's opinion of the Remontoire was different from but efteemed by 

 that of Mr. Arnold; for he expeded to arrive at perfe6lion •^'"''''^''"' 

 in his maclune froui introducing it, though by his method of 

 application, he did not detach his efcapement from the whole 

 of the train of wheels. The invention was undoubtedly a 

 great proof of his fuperior ingenuit)-, and merited high praife. 

 However, on finding the going of his watch not to anfwer 

 his expectation, he attributed its irregulajity to the thermo- 

 meter not liaving its due effect; and aiferted, " that if it 

 could properly be put into the balance, the watch would go ^ 

 within a few feconds a year," which affertion has fmce been 

 proved erroneous. 



Mr. 



