Proceedings of the American Academy of Arts and Sciences. 

 Vol. XLIII. No. 5. —September, 1907. 



CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL LABORATORY, 



HARVARD UNIVERSITY. 



ON THE DETERMINATION OF THE MAGNETIC BE- 

 HAVIOR OF THE FINELY DIVIDED CORE OF AN 

 ELECTROMAGNET WHILE A STEADY CURRENT 

 IS BEING ESTABLISHED IN THE EXCITING COIL. 



By B. Osgood Peirce. 



NEW YORK 



BOTANICAL 



OAROEN. 



