94 



of K were caused by this bit of wood being weighed with it after 

 the first comparison of K by Captain Kater, and by the gradual 

 oxidation of the surface of K. The discrepancies presented by the 

 weighings of the brass troy pounds at different times, due to the 

 effect of oxidation or other causes, are so large, that I resolved, with 

 the consent of the Astronomer Royal, to rest for the evidence of the 

 weight of the lost standard entirely on the 300 comparisons of Sp 

 and the 140 comparisons of RS with U. 



If we consider the discordances presented by the weighings of the 

 brass troy pounds simply as errors of observation, without paying 

 any regard to their probable causes, the resulting value of U will not 

 be very different from that given by the platinum troy pounds 

 alone. 



By the observations of 1824 and 1829, 



gr. weight. 



U=Sp +0-0081 30 



U=RS +0-0030 14 



U=Sb +0-0103 6 



U=K -0-0339 9 



U=(Ex + L + Ed + D) -0-0022 6 



By the observations of 1844, 



gr- 



RS =Sp +0-0057 



Sb =Sp +0-0030 



K =Sp +0-0363 



Ex + L + Ed + D=2(Sb + K) + 0-0260 



Whence, supposing the errors of weighing in 1844 to be insensible, 

 compared with the discordances of the brass troy pounds, 

 gr. weight. 



(1) U=Sp + 0-0081 30 



(2) U=Sp + 0-0087 14 



(3) U=Sp + 0-0133 6 



(4) U=Sp + 0-0024 9 



(5) U=Sp + 0-0261 6 



The mean of all the equations gives U=Sp + 0-0096 grain. 



Excluding the last, which depends upon the weighings iu 1824, 

 U=Sp + 0-0079 grain. 



