1020 
PROFESSOR J. A. EWING AND MISS H. G. KLAASSEN 
mately expressed by the formula in question. The character and extent of the 
divergence is, perhaps, more obvious from iuspection of the curve, than from comparison 
of the numbers whicli have been given above. 
Fig. 23. 
|H dl and B for tte low cycles of Ring IV. The dotted line repi’esents values of 0‘0034 
Experiments on the Heating Effect of Eeyersals of Magnetism. 
In another section of our experiments direct measurements were made of the 
amount of heat generated by reversals of magnetism. 
Some of the rings employed in the tests which have just been described were again 
used in these experiments, and under precisely the same conditions. 
The method employed (a short account of which was published in ‘ The Electrician’ 
of October 9, 1891) depended on the use of two exactly similar rings, one of which 
had its iron core subjected to magnetic reversals, while heat was developed in the 
other by the passage of a steady electric current. This steady current "was adjusted 
until the rate at which heat was generated by the current in one ring became the 
same as the rate at which heat was generated by reversals of magnetism in the other 
ring, equality of temperature as between the two rings being tested by means of a 
thermoelectric circuit with a jiair of junctions, one embedded within the core of each 
ring. The current which was used to magnetize the one ring passed also round the 
