( 824 ) 
The mean with the exception of the two values placed between 
brackets is 345.9 and it gives 
X 64 o. 9K . = 275,0.10 6 
while the method of the magnetic rise gave 
X64°.9K. = 283,5.10-6 
The difference is 3%; but in this connection we must remember 
that the correction for non-uniformity is about 16%, and that the 
temperature of the liquid becomes very uncertain at the pressure of 
11 mm. under which the liquid boils at this temperature. 
Finally, we now give two series of measurements which were 
made with other pole-gaps so as to obtain other deviations in 
the uniformity of the field. They were hastily made and under un¬ 
favourable circumstances, since oscillations and disturbances caused 
by the running of machines in the neighbourhood interfered with 
the observations. We give them move as examples of how the method 
of calculation followed still leads to good results even when the 
couples due to non-uniformity of the field are extremely large (28 / , 
of the chief couple). 
