In 1829. In 1844. 



gr- gr- 



RS=Sp +0-0051 RS=Sp +0-0057 



Sp=Sb +0-0022 Sp=Sb +0-0030 



RS=Sb +0-0073 RS=Sb +0-0032 



K =Sp +0-0420 K =Sp +0-0362 



K =RS + 0-0369 K =RS + 0'0304 



K =Sb +0-0442 K =Sb +0-0317 



In the interval between 1829 and 1844, the difference between the 

 two platinum troy pounds Sp and RS had undergone no very sen- 

 sible relative change. If, as appears probable, Sp and RS have 

 undergone no sensible absolute change, Sb has gained 0*0046 grain, 

 and K has lost 0'006l grain. On the same supposition it appears 

 that 



In 1824. In 1844. 



With the single exception of K, all the brass weights have become 

 heavier since they were compared with U, in consequence probably 

 of the oxidation of their surfaces, while U, which was made in 1 758, 

 was protected from further change by the coat of oxide already 

 formed. One of these weights, Sb, appeared to have been protected 

 by gilding, though imperfectly, since parts of its surface were slightly 

 tarnished. Ex and L were brighter than Ed and D. K, though it 

 had become lighter, was much tarnished. The discordances pre- 

 sented by the different weighings of K appear to have greatly per- 

 plexed both Professor Schumacher and Captain Kater, and were 

 probably the cause of the numerous and accurate comparisons of the 

 several troy pounds placed at the disposal of the Committee with the 

 lost standard, on which alone depends the possibility of restoring it 

 with sufficient accuracy. Previous to the comparison of K in 1844, 

 a small fragment of wood, like a grain of coarse sawdust, was found 

 adhering so firmly to its under surface, that it was detached with 

 some difficulty. It appears probable that the changes of the weight 



