144 Contributions to Electricity and Magnetism. 



times less; and these inferences I have found in accordance with 

 the results of experiments, (75.) If, however, instead of placing 

 the helix on one spire of the long conductor, it be submitted at 

 once to the influence of all the twenty spires, then the intensity 

 of the shock should be twenty times greater, since twenty times 

 the quantity of current electricity collapses, if we may be allow- 

 ed the expression, in the same time, and exerts at once all its in- 

 fluence on the helix. If, in addition to this, we add the conside- 

 ration that the whole quantity of current electricity in a long 

 conductor is greater than that in a short one, (73,) we shall have 

 a further reason for the increase of the terminal shock, when we 

 increase the length of the battery conductor. 



75. The inference given in the last paragraph, relative to the 

 change in the quantity of the induction, but not in the intensity 

 of the shock from a single spire, by increasing the whole length 

 of the conductor, is shown to be true by repeating the experiment 

 described in paragraph 13. In this, as we have seen, the inten- 

 sity of the shock remained the same, although the length of the 

 circuit was increased by the addition of coil No. 2. When, how- 

 ever, the galvanometer was employed in the same arrangement, 

 the whole quantity of induction, as indicated by the deflection 

 of the needle, was diminished almost in proportion to the increas- 

 ed length of the circuit. I was led to make this addition to the 

 experiment (13) by my present views. 



76. The explanation given in paragraph 74, also includes that 

 of the peculiar action of a long conductor, either coiled or ex- 

 tended, in giving shocks and sparks from a battery of a single 

 element, discovered by myself in 1831; (see Contrib. No. II.) 

 The induction, in this case, takes place in the conductor of the 

 primary current itself, and the secondary current which is produ- 

 ced is generated by the joint action of each unit of the length of 

 the primary current. Let us suppose, for illustration, that the 

 conductor was at first one foot long, and afterwards increased to 

 twenty feet. In the first case, because the short conductor would 

 transmit a greater quantity of electricity, the secondary current 

 produced by it would be one of considerable quantity, or power 

 to deflect a galvanometer ; but it would be of feeble intensity, 

 for although the primary current would collapse with its usual 

 velocity, (69,) yet, acting on only a foot of conducting matter, 

 the eff"ect (74) would be feeble. In the second case, each foot 



