Proceedings of the American Academy of Arts and Sciences. 

 Vol. XLIV. No. 13. — March, 1909. 



CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL 

 LABORATORY, HARVARD UNIVERSITY. 



ON THE MAGNETIC BEHA VIOB OF HARDENED 



CAST IRON AND OF CERTAIN TOOL STEELS 



AT HIGH EXCITATIONS. 



By B. Osgood Peirce. 



