88 HENRY A. KOWLAND 



At centre of field between the poles 12500 



On the axis near one pole 32100 



On cone one inch from vertex 11000 



On cylindrical portion of magnet 2f inches from the 



vertex of the cone 5800 



These poles were now replaced by frustums of cones with flat ends, 

 the original diameter of the iron, 2 inches, being reduced at the end to 

 If inches, and they were placed \ inch apart. The field in this case 

 between them was 61000, or nearly up to the maximum of magnetiza- 

 tion of nickel at common temperatures, and above that at high tem- 

 peratures. 



Troy, April 1, 1875. 



