204 PROCEEDINGS OF THE AMERICAN ACADEMY. 



however, as some instances given show, always indicate that the 

 distribution of the magnetic induction in the bar is very irregular. 



My thanks are due to the Trustees of the Bache Fund of the National 

 Academy of Sciences who have kindly lent me some of the apparatus 

 used in making the observations described in this paper. 



The Jefferson Laboratory, 



Harvard College, 

 Cambridge 



