240 Intelligence and Miscellaneous Articles. 



Both the spirals were coiled on brass sheaths slit lengthwise. The 

 external magnetizing spiral, which consisted of covered copper wire 

 2'4 millims. in diameter, was 580 millims. in length by 225 

 millims. external and 110 millims. internal diameter. The interior 

 spiral consisted of covered copper wire I millim. in thickness and 

 600 millims. in length ; this had an external diameter of 30 millims., 

 and an internal one of 19 millims. 



The bars of iron and steel were all several inches shorter than the 

 inner spiral. 



The results of this investigation may be summed up as follows : — 



With a closed magnetizing spiral, stretching and relaxing, the 

 stretching produces an increase of the magnetic momentum up to a 

 certain point; in like manner, opening and closing a voltaic current 

 sent through iron or steel bars produces an increase of its mag- 

 netic momentum up to a certain amount. 



If this limit has been attained, in further stretchings (as well as in 

 openings and closing of the current which is passed through) the 

 magnetism oscillates about this limit ; in a steel or iron bar, stretch- 

 ings diminish the magnetism, if it is thin and strongly magnetized, 

 while relaxation of the stretching produces just as great an increase. 

 But if the bar is thick and powerfully magnetized, an increase is 

 produced on stretching, and on relaxation a diminution. 



Yet, in transmitting a current, there is a difference between steel 

 and iron when this limit has been attained. In the case of iron, 

 there is an increase on closing the current, and on opening just as 

 great a diminution, whatever be the direction of the current. Steel 

 exhibits the same behaviour if the current enters at the south pole 

 of the magnet ; but if it enters at the north pole, there is conversely 

 a diminution on closing, an increase on opening. 



In the case of an open magnetizing spiral, stretching and relaxa- 

 tion produce a diminution of magnetism, to a certain amount. In 

 like manner the passage of a current and its interruption produce a 

 diminution of magnetism, up to a certain magnitude. 



When this has been reached, on further stretching or on repeated 

 opening or closing the current, the magnetism oscillates about this 

 limit; and in soft iron stretching produces an increase, while relax- 

 ation produces just as great a decrease. Hard steel exhibits exactly 

 the opposite behaviour ; and between hard and soft steel all inter- 

 mediate stages may be observed. Closing a current produces, in the 

 case of iron, an increase of magnetism ; opening it, just as great a 

 decrease, whatever be the direction in which the current passes 

 through the bar. The same is the case with steel if the positive 

 current enters at the south pole. 



Up to a certain limit stretching acts like a relaxation, and open- 

 ing and closing a current like a mechanical agitation. So far, 

 therefore, these first actions of traction and of the current are con- 

 nected with other known phenomena. The phenomena, however, 

 which occur after this limit is attained are new. 

 Those depend on another cause, which directs the molecules. This 



