Comparisons of Mercury and Platinum Thermometers. 21 



From the preceding observations we have : — 



R = 258-471 (mean box-units, at 20° 0., of box No. 7), 

 R x = 358-231 „ ,, „ „ 



This gives 



§i= 1-385962. 



Mr. E. H. Griffiths was kind enough to standardize this 

 thermometer with great care before sending it, and the values 

 found by him (as a mean of many observations with different 

 combinations of coils and bridge-wire of Box No. G) were : — 



January 21, 1896. 



B, x = 358 075 mean box-units Box 6, 



E = 258-366 „ „ 



Pt sulphur = 422-54 (barometer at 771*35 mm.): 



hence 



8 = 1-490. 



" In this determination the average temperature of the box 

 was about 15°"4, but it was rapidly varying. Moreover, the 

 temperature correction was very large, the box being- right at 

 20° C." 



January 



23, 



1896. 







Ri 



= 258-362, 







R 



= 358-078, 





Hence 



R* 



= 679-510 



(barometer at 769*20) 





R, 



E 



= 1-38596, 





8 = 1-491. 



The remarkable agreement of our value of ~ with that 



±t 



found by Griffiths renders it unnecessary for us to determine 



the resistance of the thermometer in boiling sulphur (the 



third temperature usually employed), and we therefore 



accepted the value of S, 1-491, given by Griffiths, as correct. 



[It is interesting to note that for the standardization given 



under date of January 21, the value of 



pt = - p^ -xlOO = -259°-12, 

 ill — l^o 



