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



Diameter in centimeters. 



0*33 

 0-33 

 0-33 

 0-26 

 0'23 

 0*18 

 0-18 



Mi o — M x oo 



M 10 

 0-00024 

 0-00022 

 0-00022 

 0-00015 

 0-00012 

 0-00010 

 0-00010 



0.0020 



\ 







1 



0.0015 









O.OOIO 









0.0005 



i 



> 1 



9 1 



5 20 



Much smaller coefficients than those here indicated are often 

 obtained. I have a seasoned magnet 10 cm long made of Cres- 

 cent Drill Rod 2*0 mm in diameter the moment of which appears 

 to be constant between 10° C. and 100° C. The moment per 

 gram of this magnet is 29*3 c. g. s. units. A somewhat stronger 

 magnet made from a piece of the same rod has a small but 

 unmistakably positive coefficient. I have been unable to pro- 

 cure any very slender pieces of self-hardening steel, but if we 

 may judge by the trend of observations made on thick speci- 

 mens, a thin wire of this steel would yield magnets with very 

 small temperature coefficients. 



