334 CONTRIBUTIONS TO ELECTRICITY AND MAGNETISM. 



125. These effects were evidently not due to the accumulated inten- 

 sity at the extremities of the wire, on the principles of ordinary elec- 

 trical distribution, since the knuckle required to be brought within 

 about a quarter of an inch before the spark could be received. It was 

 not alone the quantity, since the experiments of Wilson prove that the 

 same effect is not produced with an equal amount of electricity on the 

 surface of a large conductor. It appears evidently therefore a case of 

 the induction of an electrical current on itself. The wire is charored 

 with a considerable quantity of feeble electricity, which passes off in the 

 form of a current along its whole length, and thus the induction takes 

 place at the end of the discharge, as in the case of a long wire trans- 

 mitting a current of galvanism. 



126. It is well known that the discharge from an electrical battery 

 possesses great divellent powers ; that it entirely separates, in many 

 instances, the particles of the body through which it passes. This 

 force acts, in part, at least, in the direction of the line of the discharge, 

 and appears to be analogous to the repulsive action discovered by Am- 

 pere, in the consecutive parts of the same galvanic current. To illus- 

 trate this, paste on a piece of glass a narrow slip of tinfoil, cut it through 

 at several points, and loosen the ends from the glass at the places so 

 cut. Pass a discharge through the tinfoil from about nine half gallon 

 jars ; the ends, at each separation, will be thrown up, and sometimes 

 bent entirely back, as if by the action of a strong repulsive force be- 

 tween them. This will be understood by a 

 reference to Fig. 14; the ends are shown 

 bent back at «, a, a, a. In the popular expe- 

 periment of the pierced card, the bur on each 



b glass piate^ a^^a,a, a, openings ^jj^ appcars to bc cluc to an actlou of the same 



kind. 



127. It now appears probable, from the facts given in paragraphs 

 119 and 120, that the table in paragraph 92 is only an approximation 

 to the truth, and that each current from galvanism, as well as from 

 electricity, first produces an inductive action in the direction of itself, 

 and that the inverse influence takes place at a little distance from the 

 wire. 



128. To test this the compound helix was placed on coil No. 1, to 



