204 



PEOCEEDINGS OF THE AMERICAN ACADEMY. 



TABLE I. 



Demagxetizixg Factors. (X.) 



tizing force at the middle point of the rod as the other suffers. This 

 induced magnetism (both o- and p) near the centre of a rod of iron 

 magnetized to a value of B somewhat below 10,000, can be readily 

 recognized by its effect on a small compass needle, which will be de- 

 flected the moment it is moved a few centimeters from the middle 

 part of the rod toward either end. 



It might be of interest to note that the highest possible demagne- 

 tizing force would be obtained by placing a very large slab of iron, with 

 plane parallel faces, perpendicular to the lines of an infinite magnetizing 

 field H' ; the value of Hi would be 4kTrI^ , when the slab is infinite in 

 extent, but has any finite thickness. This Hi would, moreover, have 



