258 Mr. Louis Bell on the Absolute 



comparisons with C.S. and with u Bronze 11," one of the 

 primary copies of the Imperial Yard, which had been recom- 

 pared with that standard in 1878. 



From the comparisons of S x and S 2 made in 1885 the 

 following values of those standards were deduced: — 



&\ + frmn=\k , and 



S a 2 + 0-2/* = iA . 

 Hence S a 2 =S a 1 + 0'78 / a; 



and for the first decimetre were found the relations: — 



Dm 1 S a 1 + 0'05 A t= 1 1 (J A , 



Dm 1 S a 2 -0-01/A=^ F A 0} 



Whence Dm 1 S a a = Dm 1 S a 1 + 0-06/A. 



On these equations were based the results embodied in my 

 former paper. In the latter part of May 1887, these stan- 

 dards were very carefully compared with each other, and with 

 a speculum-metal bar graduated by Prof. Rowland, as I 

 desired to take one or more of the standards to Berlin during 

 the summer in order to get a comparison with the standard 

 used by Miiller and Kempf. 



The results of this examination were of a somewhat startling 

 character, as follows: — 



!S a 2 = S a x 4- 1'2/x, direct, 

 S a 2 =S a 1 + l'l/A, through the Rowland bar 

 designated R B . Also, 



Dm 1 S a 2 = Dm 1 S a 1 + 1"7/a, through R B . 



In 1885 Rogers had found for the relation between the two 

 decimetres of each bar: — ■ 



Dm 2 S a 1 = Dm 1 S a 1 -0-56/A, 

 DmiS^Dm^ + CHG/*. 

 I now found for the same quantities: — 



Dm 2 S a 1 = Dm 1 S a 1 + 0'64/i, direct, 

 DmgS^DmiS^ + O.GO^, from R B , 

 DmiS^DmsS^ + l-GO/A, direct, 

 Dm 1 S a 2 = Dm 2 S* 2 + l-(;5/A, from R B . 



All these relations being for 16°'67 C. 



The standard S a 2 was taken to Berlin during the summer; 

 and through the kindness of Dr. Nieberding, Director of the 

 Normal Aichungs Commission, I was enabled to havo it com- 

 pared with R 78 , the standard metre to which the wave-length 



