Dr. Moll on the Comparison of Weights. 65 



The beam of the balance which I employed is about eighteen 

 inches in length ; the knife-edge of the axis is about two 

 inches and a half long ; the knife-edges on which the scale 

 pans are suspended are about one inch. When loaded with a 

 kilogramme in each scale, ^^ of a grain are sufficient to 

 show a derangement in the equilibrium of the beam. 



In order to ascertain as much as possible how far the weights 

 of Mr. Robinson might be relied on, and within what limits 

 the errors, arising from some inaccuracy in the weights, were 

 likely to be circumscribed, I requested Mr. Bate of the Poultry 

 to make for me a very accurate brass copy of the one pound 

 British imperial troy weight; and it is but justice to say, that 

 this standard greatly excels in point of workmanship, and the 

 care with which it is preserved from external injury, the rather 

 unsightly appearance of the standard kilogramme of Monsieur 

 Fortin's making. 



This troy pound of Mr. Bate was found, by a mean of very 

 many weighings, to be equal to 5759.935 of Mr. Robinson's 

 grains, making a difference of 0.065 grains, or T f $<j of a grain, 

 or OTTT ^ *^ e wno ^ e ' I regret that it lies not within my 

 power to ascertain whether this slight difference lies with Mr. 

 Bate or Mr. Robinson. But it will, however, appear that a 

 difference like this has but small influence on the general re- 

 sult, as far as concerns the kilogramme. 



It will scarcely be necessary for me to preface, that, in all 

 these weighings, I constantly employed Borda's method, of 

 avoiding any error arising from the inequality in the length of 

 the arms of the balance beam. 



With every precaution, then, I found the authentic brass 

 copy of the kilogramme, brought from Paris by Mr. Van 

 Swinden, adjusted by the celebrated commission of weights 

 and measures, and made by M. Fortin, to be equal to 



1st weighing 15432.350^ 

 2d 15432.320 

 3d 15432.305 



r *u " \ i! too oUn of Mr - Robinson's British imperial troy grains. 

 oth , 



6th 15432.265 



Mean 15432.295 

 VOL. II. AUG. 1831. F 



