LIMITS OF INSULATION AND DISCHARGE IN AIR. 97 



subject to the inductive action are aflfected to the same amount, or acquire the same 

 tension. What has been called the lateral action of the lines of inductive force (1231. 

 1297.), and the diverging and occasionally curved form of these lines, is against such 

 a notion. The idea is, that any section taken through the dielectric across the lines 

 of inductive force, and including all of them, would be equal, in the sum of the forces, 

 to the sum of the forces in any other section ; and that, therefore, the whole amount 

 of tension for each such section would be the same. 



1370. Discharge probably occurs, not when all the particles have attained to a cer- 

 tain degree of tension, but when that particle which is most affected has been exalted 

 to the subverting or turning point (1410.). For though all the particles in the line of 

 induction resist charge, and are associated in their actions so as to give a sum of re- 

 sisting force, yet when any one is brought up to the overturning point, all must give 

 way in the case of a spark between ball and ball. The breaking down of that one must 

 of necessity cause the whole barrier to be overturned, for it was at its utmost degree 

 of resistance when it possessed the aiding power of that one particle, in addition to the 

 power of the rest, and the power of that one is now lost. Hence tension or intensity* 

 may, according to the theory, be considered as represented by the particular condi- 

 tion of the particles, or the amount in them of forced variation from their norma! 

 state (1298. 1368.). 



1371. The whole effect produced by a charged conductor on a distant conductor, 

 insulated or not, is by my theory assumed to be due to an action propagated from 

 particle to particle of the intervening and insulating dielectric, the particles being 

 considered as thrown for the time into a forced condition, from which they endeavour 

 to return to their normal or natural state. The theory, therefore, seems to supply an 

 easy explanation of the influence of distance in affecting induction (1303. 1364.). As 

 the distance is diminished induction increases; for there are then fewer particles in 

 the line of inductive force to oppose their resistance to the assumption of the forced 

 or polarized state, and vice versa. Again, as the distance diminishes, discharge across 

 happens with a lower charge of electricity ; for if, as in Harris's experiments (1364.), 

 the interval be diminished to one half, then half the electricity required to discharge 

 across the first interval is sufficient to strike across the second ; and it is evident, also, 

 that at that time there are only half the number of interposed molecules uniting their 

 forces to resist the discharge. 



1372. The effect of enlarging the conducting surfaces which are opposed to each 

 other in the act of induction, is, if the electricity be limited in its supply, to lower 

 the intensity of action ; and this follows as a very natural consequence from the in- 

 creased area of the dielectric across which the induction is effected. For by diffusing 

 the inductive action, which at first was exerted through one square inch of sectional 

 area of the dielectric, over two or three square inches of such area, twice or three 

 times the number of molecules of the dielectric are brought into the polarized con- 



* See Harris on proposed particular meaning of these terms. Philosophical Transactions, 1834, p. 222. 

 MDCCCXXXVIII. O 



