312 CONTRIBUTIONS TO ELECTRICITY AND MAGNETISM. 



quantity and feeble intensity; but succeeding experiments will show 

 that this is not necessarily the case. 



38. All the experiments given in this section have thus far been 

 made with a battery of a single element. This condition was now 

 changed, and a Cruickshank trough of sixty pairs substituted. When 

 the current from this was passed through the riband coil No. 1, no in- 

 dication, or a very feeble one, was given of a secondary current in any 

 of the coils or helices, arranged as in the preceding experiments. The 

 length of the coil, in this case, was not commensurate with the inten- 

 sity of the current from the battery. But when the long helix. No. 1, 

 was placed instead of coil No. 1, a powerful inductive action was pro- 

 duced on each of the articles, as before. 



39. First, helices No. 2 and 3 were united into one, and placed 

 within helix No. 1, which still conducted the battery current. With 

 this disposition a secondary current was produced, which gave intense 

 shocks but feeble decomposition, and no magnetism in the soft iron 

 horseshoe. It was therefore one of intensity, and was induced by a 

 battery current also of intensity. 



40. Instead of the helix used in the last experiment for receiving 

 the induction, one of the coils (No. 3) was now placed on helix No. 1, 

 the battery remaining as before. With this arrangement the induced 

 current gave no shocks, but it magnetized the small horseshoe ; and 

 when the ends of the coil were rubbed together, produced bright 

 sparks. It had therefore the properties of a current of quantity ; and 

 it was produced by the induction of a current, from the battery, of in- 

 tensity. 



41. This experiment was considered of so much importance, that 

 it was varied and repeated many times, but always with the same re- 

 sult ; it therefore establishes the fact that an intensity current can in- 

 duce one of quantity, and, by the preceding experiments, the converse 

 lias also been shown, that a quantity current can induce one of inten- 

 sify. 



42. This fact appears to have an important bearing on the law of 

 the inductive action, and would seem to favour the supposition that 

 the lower coil, in the two experiments with the long and short secon- 



