B. 0. Peirce — Properties of Seasoned Magnets. 339 



does not seem likely that a very long magnet made of the 

 Jessops self-hardening steel, which I experimented on, would 

 have a much lower temperature coefficient than the longest 

 specimens I used. 



The only very stout magnets with negative temperature 

 coefficients that I have seen described are the comparatively 

 weak ones made by Lamont of a kind of laminated steel and 

 iron used in Russia. One of the advantages of very slender 

 magnets, like those used so skillfully by Professor T. Gray, is 

 that their temperature coefficients are comparatively small, as 

 Cancani and others have shown. The relative loss of moment, 

 when heated from the room temperature of 10° C. to 100° C, 



0.0025 



\ 







-1 



0.0020 \ 



\ 



\ 







0.0015 









O.OOIO 









0.0005 



i 



1 



1 



5 20 



of a number of very strong, seasoned magnets 10 cm long made 

 of " Crescent Drill Eod " are shown in the following table. 

 These results seem to point to small if not to negative coeffi- 

 cients in the case of very thin wire. 



Am. Jour. Scr.— Fourth Series, Vol. V, No. 29.— May, 1898. 

 23 



