164 CIIRONOMETRY. 



accurate? viz. that Mr. Harrison attempted to provide 

 the compensation for heat and cold in the- balance, and 

 that he miscarried so decidedly, that he was obliged to 

 apply it to the spiral spring. How he endeavoured to 

 accomplish it, is not known ; therefore, any other person 

 might be afterwards the real inventor of the same con. 

 trivance, and have the additional merit of succeeding in 

 an undertaking where so great a genius had failed. Upon 

 this ground, although the letter above quoted has been 

 now published some years, and the report contained in it 

 had been circulated long before its date, the invention of 

 the compensation balance has been, in this country, gene- 

 rally ascribed to the late Mr. Arnold; aijd certain it is, 

 It is generally that if there existed no other reason to invalidate his claim, 

 English to Ar- ^^^ memory of that artist woyld continue to be accom* 

 nold; panied with the credit of that important invention. But 



f *^L ''l^^^°— ^ the invention of the first compensation balaaee that ever 

 was executed, (that of the fluid thermometer), as well as 

 that of the compensation balance upon the principle now 

 universally used, are clearly due to P. le Roy; and the 

 •— and subse- merits of the late Mr. Arnold, as an original author, in 

 noW h^wesup- ^^'^ respect, merely rest upon the supposition that he 

 pose him to possibly may have had no ^previous knowledge of P. le 



have been ig- Roy's w ritings. This, however, is foreign to our present 

 norant of that ,/ , i ,, , -, , ,. , . . 



artist's works, object ; and jve shall conclude by remarking, that it is 



If Harrison very probable Mr. Harrison never thought of using his 



jt^he wqiild° wictallic thermometer in the construction of the balance; 



have complet- this method being so simple and certain, that, if he had 



^ ^^' hit upoQ it, it could not have failed in his hands. From 



a passage in his last work*, it also clearly appears, that 



what he had in vain sought for was, the construction of a 



balance similar to his gridiron pendulum ; and, as this 



^ but his re- passage has been frequently quoted in a mutilated man- 



dlrecte^r^th i^^r, to shew the great difficulty and importance of the 



gridiroc. present method of compensation, we shall transcribe it 



entire, in order to produce the grounds upon which our 



opinion is founded: ^' And I can now boldly say, that if 



the provision for heat and cold could properly be in the^ 



♦ A Description concerning such Mechanism as will afford ^ 

 -liice, or truQ Mensuration of Time, &c. 176J, p. 103. 



balance 



