1904.] some Mercury Standards of Resistance, etc. 241 



" end corrections " to the resistance. The ends of the tubes passed 

 into comparatively large vessels containing mercury, into which two 

 leads were introduced. 



For the measurement of resistance, three methods were employed ; 

 the Kelvin double bridge, the potentiometer, and the Carey Foster 

 bridge. The last of these methods is shown to be subject to a 

 considerable error when mercury standards are measured. 



The following table contains the results of the resistance measure- 



Standard. 



Res. in ohms 

 (Kelvin 

 double bridge). 



Res. in ohms 

 (potentio- 

 meter) . 



Mean 

 value of res. 



Difference 

 parts in 



from mean 

 100,000. 



M 



1 -001162 



1 -001167 



1 -001164 



-Oo 



+ 3 





1 '001164 



1 -001162 





-t0 



— Oo 





1 -001166 



1 -001165 





+ 0, 



+ oi^ 



P 



1 -000467 



1 -000468 



1 -000470 



-o 3 



-0, 





1 -000468 



1 -000472 





-Oo 



+ 0o 





1 -000472 



1 -000471 





+ 0o 



+ o^ 



T 



1 -000277 



1 -000273 



1 -000278 



-9i 



-o 5 





1 -000281 



1 -000280 





+ 0, 



+ 0., 





1 -000276 



1 -000231 





— 0., 



+ Oo 



u 



1 -000215 



1 -000213 



1 -000217 



-0 2 



-o. 



p '• 



1 -000216 



1 -000216 





-0, 



— 0, 





1 -000222 



1 -000218 





+ 0- 



+ 0, 



Y 



1 -001462 



1 -001455 



1 -001462 



±o 



-o? 





1 -001468 



1 -001462 







+ 0,. 





1 -001463 



1 -001465 





+ 





W 



1 -000156 



1 -000161 



1 -000153 



+o 3 



+ o a 





1 -000152 



1 -000151 





— 0, 







1 -000146 



1 -000151 





— 0- 





X 



1 -001147 



1 -001147 



1 -001151 



-0 4 



-0 4 





1 -001154 



1 -001151 





+ o. 



±o 





1 -001155 



1 -001152 





+ o 4 



1-0, 



Y 



1 -000356 



1 -000354 



1 -000350 



+ 6 



+ 4 





] -000347 



1 -000350 





-Qa 



=b0 





1 -000348 



1 -000346 





-0 2 



-o 4 



z 



] -0013S7 



1 -001391 



1 -001389 



-o 3 



+ 0o 





1 -0013S9 



1 -001384 





±o 



-05 





1 -001392 



1 -001393 





+ 0, 



+ o 4 



G- 



1 -001130 



1 -001135 



1 -001135 





±0 





1 -001138 



1 -001135 





+ o 3 



±0 





1 -001131 



1 -001132 





-p 4 





s 



1 -001053 



1 -001054 



1 -001057 



-o 4 







1 -001055 



1 -001061 





-Oo 



+ 4 





1 -001061 



1 -001057 





+ 4 



±o 



