318 Co7itrihutions to Electricity aiid Magnetism. 



coil, of great quantity and feeble intensity ; but succeeding ex- 

 periments 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 substitu- 

 ted. When the current from this was passed through the riband 

 coil No. 1, no indication, or a very feeble one, was given of a 

 secondary current in any of the coils or helices, arranged as ia 

 the preceding experiments. The length of the coil, in this case, 

 was not commensurate with the intensity 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 produced 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 horse-shoe. 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 receiv- 

 ing the induction, one of the coils (No. 3) was now placed on he- 

 lix No. 1, the battery remaining as before. With this arrange- 

 ment the induced current gave no shocks, but it magnetized the 

 small horse-shoe; 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 intensity. 



41. This experiment was considered of so much importance, 

 that it was varied and repeated many times, but always with the 

 same result ; it therefore establishes the fact that an intensity 

 current can induce one of quanity, and, by the preceding experi- 

 ments, the converse has also been shown, that a quantity current 

 can induce one of intensity. 



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

 of the inductive action, and would seem to favor the supposition 

 that the lower coil, in the two experiments with the long and 

 short secondary conductors, exerted the same amount of induc- 

 tive force, and that in one case this was expended (to use the lan- 

 guage of theory) in giving a great velocity to a small quantity of 

 the fluid, and in the other in producing a slower motion in a larger 



