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coils upon the limbs of horseshoe mngnets, near the poles of which the 

 armature revolves. The above tables show that there is a slijiht in- 

 crease of magnetism as the bar heats. Preliminary tests showed that 

 the increase was slow, but gradual, up to the temperature of dull red 

 heat ; then, as the bar was heated to the temperature of white heat, its 

 magnetic susceptibility fell, and apparently became less as the temper- 

 ature increased beyond that of white heat. On cooling, the bar quickly 

 regained its normal magnetic state of susceptibility. Thus, the curve 

 which represents such a change would rise nearly as a straight line, 

 inclined to the axis of X at a slight angle, up to the point of dull red 

 heat ; then it would fall quickly, in nearly a straight line, to the point of 

 white heat ; rising quickly again to the point of dull red heat, forming 

 a V-shaped inflection in the curve, and then fiiUing again, in nearly a 

 straight line, towards the axis of X. One of Thomson's reflecting 

 galvanometers was used in the above experiments. The results of the 

 above show that the heating of the armatures of a magneto-electric 

 engine increases rather than diminishes its magnetic susceptibility. 



