independent of Changes of Temperature. 221 



ordinates it is easy to estimate what may be called the " character- 

 istic " temperature coefficient and permanent loss for this kind of 

 wire. 



It may be inferred that in general the temperature effects upon 

 magnets are principally influenced by the demagnetising factor over 

 a considerable range of dimension ratios, and beyond that range by 

 the nature of the material. 



In the fourth diagram the curves of initial and final intensities are 

 plotted with dimension ratios as abscissae, and they resemble so 

 closely the curve traced in the same way by Barns* for steel of 

 *• blue annealed " temper, that it is very probable this is the temper 

 given to the music wires upon which these experiments have been 

 made. 



The chief points elicited by this investigation may now be sum- 

 marised : — 



1. The temperature coefficient is generally least in the hardest 



* Barus and Stronhal, < Bulletin U.S. Geol. Survey,' Mo. 14, 1885. 



