142 



ON MAGNETISM. 



original induction we may use them instead of the 

 original induction. 



65. A mass of iron, symmetrical with respect to the 

 plane directed to the axis of a compass and with respect 

 to the horizontal plane, and with its center at the same 

 height as the compass, is subject to terrestrial induction : 

 theoretical investigation of its deviating energy on the 

 compass: it follows the law of sine 2 azimuth. 



In each of the diagrams of Figure 53, the curve 



Fig. 53. 



represents the outline of the mass, and the magnetized 

 needle at which it points is the compass-needle. 

 The terrestrial energy is in the direction of the local 

 dip, and the whole inductive energy will be in that 



