B. O. Peirce — Properties of Seasoned Magnets. 337 



degree increased with the temperature. If, therefore, a curve 

 be plotted the abscissas of which give the temperatures and 

 the ordinates the differences between the moment (M ) of any 

 magnet at some given lower temperature (t ) and the moments 

 (M) of the same magnet at these temperatures, this curve will 

 be concave upward. 



Tables I and II give the results of a series of observations 

 made by Mr. C. G. Persons on two short, stout, magnets made 

 of self-hardening steel, which are fairly representative. In 

 figures 2 and 3, where these results are shown graphically, the 

 temperatures are used as abscissas and the corresponding values 

 of the ratio of M — M to M as ordinates. It is worthy of 



2. 











O.JO 









0.075 









0.050 









0.025 



/ 2 



5 5 



7 



5 100 



notice that these curves depart so widely from straight lines 

 that the temperature coefficient, — j-r- . —5-, is in each case 



