( 821 ) 
For the constant of the spring we found 1184,5 c.g.s. 
The platinum-iridium stretching wire gives a torsion couple as 
well as the spring; the correction for this was determined by the 
same method as was used in the analogous case by Weiss and 
Kamerlingb Onnes (loc. eit.) and it was found to be 0.0152 times 
the constant of the spring. The difference between the values of the 
constant at 18° C. and -at —190° C. is smaller than the errors of 
observation. The calculations were therefore carried out with the 
constant 1184.5 (1 -f 0.0152) = 1202.5. 
6. Oscillations , The silver ellipsoid should.be protected sufficiently 
from the influence of oscillations arising from external causes by the 
occurrence of intensive Foucault currents, but the occurrence of 
these currents, which were unusually strong gave rise to great difficulties 
in the observations. In the first place the holder was extremely slow to 
reach its position of equilibrium. Further, the smallest change in the 
current flowing through the electromagnet occasioned a sudden kick 
in the whole moveable apparatus, an immediate result of the oblique 
position of the ellipsoid with respect to the lines of force. Hence the 
regulation of the current had to be done with the greatest care. 
We retained the oil-damper but removed the fixed partitions, for 
the capillary action of these gave rise to couples that, although 
small, were still not negligible. 
Results of the observations. 
