THE ART OF WEIGHING AND MEASURING. 613 



while those with RS gave 



T = 11 — 0.52870 grain. 



To the first of these expressions double weight was assigned, because 

 the comparisons of T and U with Sp were about twice as numerous as 

 those with RS. The resulting meau was therefore 



T = U — 0.52857 grains = 57.59.47143 grains, 

 and from that value of T the new standard avoirdupois pound of 7,000 

 grains was constructed. 



From sometime in the fifteenth century until the adoption of the 

 metric system in August, 1793, the system of weights employed in 

 France was the poids cle marc, having for its ultimate standard the pile 

 de Charlemagne, which was then kept in the mint, and is now deposited 

 in the Couservatoire des Arts et Metiers. The table of this weight was 



Grains. 



72 grains = 1 gros = 72 



8 gros =: 1 oiice = .576 



8 onces ^ 1 marc = 4608 



2 marcs =: 1 livre = 9216 



The origin of the pile de Charlemagne is not certainly known, but it is 

 thought to have been made by direction of King John ( A.D. 1350-1364). 

 It consists of a set of brass cup- weights, fitting one within the other, 

 and the whole weighing fifty marcs. The nominal and actual weights 

 of the several pieces are as follows : * 



Marcs. Grains. 



Bolteile20 marcs 20 + 1.4 



Piece cle 14 marcs 14 -\- 4.5 



de 8 marcs 8 — 0.4 



de 4 marcs ., 4-^2.1 



de 2 marcs 2 — 1.0 



de 1 marc 1 — 0.7 



Marc devise 1 — 1.7 



59 i 0.0 

 In determining the relation of the poids de marc to the metric weights, 

 the committee for the construction of the kilogram regarded the entire 

 pile de Charlemagne as a standard of fifty marcs, and considered the 

 individual pieces as subject to the corrections stated. On that basis 

 they found 



1 kilogram = 18827.15 French grains t 



and, as a kilogram is equal to 15132.34874 English troy grains, f we 

 have 



1 livre, poids de marc = 7554.22 troy grains. 

 =: 489.506 grams. 



The metric standard of weight, called a kilogram, was constructed 

 under the direction of the French Academy of Sciences simultaneously 

 with the meter, the work being done principally by LefevreGineau 

 and Borda. It was intended that the kilogram should have the same 



* 20, pp. 270~'7l. t Base dn Syst^me M6tri(jue, T. 3, p. 638. 1 44, p. 893. 



