i 



132 Contributions to Electricity and Magnetism. 



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 experiment, for 

 example, the shock was so feeble at making contact that it could 

 scarcely be perceived in the fingers, but so powerful at the break- 

 ing of the circuit as to be felt in the breast ; yet the galvanome- 

 ter was deflected about thirty-five degrees to the right, at the be- 

 ginning 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 magnetism, although the galva- 

 nometer was deflected thirty degrees. The needle being repla- 

 ced, 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 par- 

 agraphs were produced when the apparatus was so arranged as to 

 cause the induction at the beginning of the battery current to 

 predominate. In this case the galvanometer was still equally af- 

 fected 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 action of the 

 currents of the third, fourth, and fifth orders produces a very 

 small effect on the galvanometer, compared with that of the sec- 

 ondary current ; and this is not alone on account of the dimin- 

 ishing power of the successive inductions, as will be evident 

 from the following experiment. By raising the helix from the 

 coil, in the arrangement of apparatus for the secondary current, the 

 shock was so diminished as to be inferior to one produced by the 

 arrange ment for a tertiary current, yet, while with the secondary 

 current the needle was deflected twenty-five degrees, with the ter- 

 tiary it scarcely moved more than one degree, and with the currents 

 of the fourth and fifth orders the deflections were still less, resem- 

 bling the effect of a slight impulse given to the end of the needle. 



