OX THE FINENESS OF THE ONE YEN SILVER COIN. 301 



of the cu'id, and is fur from affording concordant results when several 

 assays are made of the same coin. If any pair of the diagonally cut 

 triangles should happsn to fall on the middle line of the original bar, 

 represented by the central strip in Fig. 5, they would be of an ex- 

 cessively high fineness, while the other pair of triangles, although 

 lower in fineness, would not be sufficiently low to counterbalance the 

 excess of fineness of the first pair. The result would be the indication 

 of too high a fineness for the coin. This assay being evidently too 

 high, the assayer would now cut two other pairs of mangles from 

 portions of the coin which lie between the first cuttings and assay 

 them. The result would be as a rule to give too low a fineness 

 equally evident, the mean of the two assays being probably nearer 

 the truth. In the case of the litst assay being too low, the second 

 assay would be similarly too high. Hence in the double assays 

 which were necessitated from this cause, made on 121 coins between 

 January and September, 1887, the percentage of differences in fineness 

 between two assays of the same coin were as follows : 



Difference nil 



Difference of between 01 and 0*5 per mille 



(»•G and 1-U 



11 and 1-5 



1-6 and 2-0 



2-1 and 2-5 



2*6 and 2-7 



Besides, there is always a difficulty in cutting the thick silver 

 coin in the required form by means of a pair of shears, so that the 

 weight of the cut portions is sometimes wide away from the mark. 

 Although the assays of individual coins are thus considerably 

 vitiated in correctness, the mean of a sufficient large number of coins in- 

 dividually assayed may agree closely with the assay of all these coins 



