1838] WRITINGS OF JOSEPH HENRY. 141 



this action during some experiments on atmospheric elec- 

 tricity made by a committee of the Franklin Institute, in 

 1836. Two kites were attached, one above the other, and 

 raised with a small iron wire in place of a string. On the occa- 

 sion at which I was present, the wire was extended by the 

 kites to the length of about one mile. The day was perfectly 

 clear, yet the sparks from the wire had so much projectile 

 force (to use a convenient expression of Dr. Hare) that fifteen 

 persons joining hands and standing on the ground, received 

 the shock at once, when the first person of the series touched 

 the wire. A Leyden jar being grasped in the hand by the 

 outer coating, and the knob presented to the wire, a severe 

 shock was received, as if by a perforation of the glass, but 

 which was found to be the result of the sudden and intense 

 induction. 



125. These efifects were evidently not due to the accumu- 

 lated intensity at the extremities of the wire, on the principles 

 of ordinary electrical 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 charged with a considerable quantity of feeble elec- 

 tricity, 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 transmitting 

 a current of galvanism. 



126. It is well known that the discharge from an electri- 

 cal 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 direc- 

 tion of the line of the discharge, and appears to be analogous 

 to the repulsive action discovered by Ampere, in the con- 

 secutive parts of the same galvanic current. To illustrate 

 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 



