376 lifVENTIO^J OF THE BALANCE SPRING. 



Account of the " jny discovery with the Academy before the Expose SuC' 

 controvcrsv ,, ■ . , t 



betweenLeRoy C?//rf was puWlC. 



and Eerthoiid " After these facts, which are notorious and well known to 



timepieces. " every one, why has M. L. R. presumed to say what fol- 



*' lows (page 18 of the Precis J ?" " M. B. having made tlie 



" discotcrij of the isochronism of springs a little later in- 



" deed; but if he had attempted to do it longer ago, it 



" uould have been a hard task for him to show it, as is done 



" in my Memorial ; it would be necessary for him to appro- 



" priate it to himself in some way, by the mamier of pre- 



" senting it." " M. L. R. is undoubtedly persuaded that 



" such delicate raillery would impose on the public: but when 



" we shall have observed, that the Memorial, of which he speaks 



*' here, is that of 1770 ; when we shall remark that he himself 



*' agrees that I had deposited my discovery at the beginning 



" of 1768 ; when we shall have seen that, without taking much 



*' trouble to notice it, he supposes that I could copy in 1768 



" what he did not shew till 1770 ; I doubt whether the laugh 



*' will be on his side. 



" M. L. R, continues (page 18 of the Precis) :" " instead, 



" then, of resting the fact and its circumstances, such as the 



*^ experiment shewed them to be, M. B. gives the whole a 



'• scientific air, of which it is not easy to comprehend any 



" thing." 



" I am sorry that M. L. R. has not understood me, and I 



*' will sincerely allow that it may be my fault. I am, how< 



" ever, encouraged by the praises which M. Daniel Bernouilli 



" has given to this part of my Traite des Horloges Marines : 



*' here is what he wrote me concerning it at the beginning 



*' of this year:" " This article" '" (where I establish that the 



*' force of the spiral must be in an arithmetical progression)" 



" expresses perfectly the true principle of the isochronism.'* 



'* And, in speaking of the experiments which I had made with 



" riiy elastic balance, he adds," " These experiments are cer- 



" tainly of infjiite interest ; they confirm the true principles 



" of the isochronism, and shew the limits of the greatest ex- 



" tent that we can give to the balance without injuring the 



" principle : this is where the progression of small weights 



*' bpgin to descend in an arithmetical progression, &c." *' I 



" confess 



