Prof, Miller on the Imperial Standard Pound, 551 



By the good offices of M. Arago, permission was obtained from 

 the French Government to compare the new English weights with 

 the standard kilogramme of platinum, known as the kilogramme des 

 Archives, and which will be denoted by the letter %. The compa- 

 rison was made by two perfectly independent methods. In one of 

 these ^ was compared sixty times with PC No. 1 + PC No. 2 + 

 auxiliary weight B+ a platinum weight V of nearly 192-436 grains. 

 In the other, ^ was first compared 200 times with the platinum 

 kilogramme ^, purchased for the British Government. (2B was after- 

 wards compared with PS + each of the four platinum copies of the 

 pound in succession, together with a platinum weight of about 

 1432'324 grains, the weight of which was found with great precision 

 by a process to be described presently. 



^ ^ had never been weighed in water. By observations made with 

 'i^he stereometer, it was found that at 0" C. the volume of % exceeded 

 that of ^ by a quantity equal to the volume of 21-119 grains of 

 water at its maximum density. By weighing (2B in air and in water, 

 it was found that A^= 20-548/7. Some time after these observa- 

 tions were made, the Committee received from Professor Schumacher 

 some observations of his own in manuscript, and a copy of Professor 

 Steinheil's paper, entiled *Das Bergkrystall-kilogramm,' from the 

 fourth volume of the Transactions of the Bavarian Academy of Sci- 

 ences, containing the determination of the volume of % by comparing 

 its linear dimensions with those of a platinum kilogramme of his 

 o^w ^, the density of which had been found by weighing it in air 

 and in water. The two weights being cylinders, and the linear 

 dimensions measured with an extremely delicate instrument con- 

 structed by Gambey, this kind of observation admitted of being made 

 with great accuracy. The resulting difference between the volume 

 of ^ and that of (!B, was found to be equal to the volume of 20*933 

 grains of water at its maximum density. On account of the large 

 number of observations, and the extreme care with which they were 

 made, this value of the volume ^— volume (JB is to be preferred to 

 that which was obtained by the stereometer, and has accordingly 

 teen used in reducing the observations for comparing the weights of 

 % and (t. 



,. ^ was compared with PS by the method which had proved so 

 , satisfactory in deducing the avoirdupois pound from the troy pound, 

 let I, K, L, M, N denote PS and its four platinum copies, A, B, T, A, 

 platinum weights of about 1432*322 grains each, Z a weight of about 

 1270- 708 grains, 6 a weight of 161*629 grains, made up of weights 

 the values of which had been carefully determined. ^ was compared 

 with each of the weights I-f K + A, I + L + B, 1 + M + r, I-f N-|-A, 

 each of the lbs. K, L, M, N having been previously compared with I ; 

 I with A + B + r-FA + Z; each of the weights A, B, T, A with Z + 0, 

 in this manner it was found that the kilogramme des Archives 

 weighed 15432-34874 grains, of which the new Imperial Standard 

 pound contains 7000, or kilogramme =2-20462125 lbs. This is pro- 

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

 English standard of weight. 



The value of %, as deduced from the direct comparison of ^ with 



