103 



bably the best determination of the weight of & in terms of the 

 English standard of weight. 



The value of fl, as deduced from the direct comparison of 1 with 

 K + L + B-f-V, is subject to some uncertainty, arising from the cir- 

 cumstance that the platinum, of which A, B, C, F were made, had 

 been very badly prepared and contained cavities filled with some 

 hygroscopic substance which rendered the weight of B slightly 

 variable, according to the greater or less amount of moisture present 

 in the atmosphere. According to these observations, the kilogramme 

 des Archives =15432-34816 grains. 



By the observations of Schumacher and Steinheil on the ratio of 

 the weight of & to that of Sp, subject to an uncertainty of 0*00139 

 grain, on account of an error of the press, and the comparison of Sp 

 with PS, the weight of a is either 15432-34873 or 15432-35012 

 grains, of which PS contains 7000. 



The French standard of commercial weight is a brass kilogramme 

 It, known as the kilogramme type laiton. It is deposited at the 

 Ministere de 1'Interieure. According to a comparison of it with 2T, 

 the result of which is published in the 25th volume of the Modena 

 Transactions, the apparent weight of It, when weighed in air at 

 Somerset House, the mercury in the barometer, reduced to the free- 

 zing-point, standing at 29' 75 inches, and the thermometer at 65'66 F. 

 (5=755-64 mm., f=18'7C.), is 15432-344 grains, of which the 

 English commercial standard contains 7000. 



The Society then adjourned to Thursday, May 8. 



