1840] 



WRITINGS OP JOSEPH HENRY. 165 



yet they were very diflPerent in regard to the intensity of the 

 action. Thus, when the arrangement of the apparatus was 

 such that the induction at making the battery circuit 

 was so feeble as not to give the least magnetism to the 

 needle, and so powerful at the ending as to magnetize it to 

 saturation, the indication of the galvanometer was the same 

 in both cases, 



42. Also, similar results were obtained in comparing the 

 shock and the deflection of the galvanometer. In one ex- 

 periment for example the shock was so feeble at making 

 contact that it could scarcely be perceived in the fingers, but 

 so powerful at the breaking of the circuit as to be felt in the 

 breast; yet the galvanometer was deflected about thirty-five 

 degrees to the right, at the beginning of the current, and 

 only an equal number of degrees to the left, at the ending 

 of the same. 



43. In another experiment, the apparatus being the same 

 as before, the magnetizing spiral and the galvanometer were 

 both at once introduced into the circuit of the helix. A 

 sewing needle being placed in the spiral, and the contact 

 with the battery made, the needle showed no signs of mag- 

 netism, although the galvanometer was deflected thirty de- 

 grees. The needle being replaced, and the battery circuit 

 broken, it was now found strongly magnetized, while the 

 galvanometer was moved only about as much as before in 

 the opposite direction. 



44. Also, effects similar to those described in the last two 

 paragraphs were produced when the apparatus was so ar- 

 ranged as to cause the induction at the beginning of the bat- 

 tery current to predominate. In this case the galvanometer 

 was still almost equally affected at making and breaking 

 battery contact, or any difference which was observed could 

 be referred to a variation in the power of the battery during 

 the experiment. 



45. Another fact of importance belonging to the same class 

 has been mentioned before, (24,) namely, that the actions of 

 the currents of the third, fourth, and fifth orders produce a 

 very small effect on the galvanometer, compared with that 



