-1859] WRITINGS OF JOSEPH HENRY. 381 



is not surprising when we consider the great length of the 

 conductor, and consequently the many points through 

 which it must pass along the surface of the earth peculiarly 

 liable to receive the discharge from the heavens. Besides 

 this, from the great length of the conductor, its natural elec- 

 tricity, driven to the farther end or ends of the wire, will be 

 removed to a great distance from the point immediately 

 under the cloud, and hence this will be rendered more in- 

 tensely negative and its attractive power thereby highly in- 

 creased. It is not probable however that the attraction, what- 

 ever may be its intensity, of so small a wire as that of the 

 telegraph can of itself produce an electrical discharge from 

 the heavens, although if the discharge were started from 

 some other cause, (such as the attraction of a large mass of 

 conducting matter in the vicinity,) the attraction of the wire 

 might be sufficient to change the direction of the descending 

 bolt and draw it, in whole or in part, to itself. It should 

 be recollected also that on account of the perfect conductivity 

 of 'the wire, a discharge on an}' one point of it must affect 

 every other part of the connected line although the whole 

 may be several hundred miles in length. 



That the wire should give off a discharge to a number of 

 poles in succession is a fact that might have been anticipated, 

 since the electricity would by its self-repulsion tend to send 

 a portion of itself down the partial conducting pole, while 

 the remaining part, attracted by the wire in advance of itself, 

 rendered negative by induction, would continue its passage 

 along the metal until it met another pole, when a new di- 

 vision of the charge would take place, and so on. The several 

 explosions in succession, heard at the same pole, are explained 

 by the fact that the discharge from the cloud does not gen- 

 erally consist of a single wave of electricity, but of a number 

 of discharges in the same path in rapid succession, so as in 

 some cases to present the appearance of a continuous dis- 

 charge of a very appreciable duration ; and hence the wire 

 of a telegraph is capable of transmitting an immense quan- 

 tity of the fluid thus distributed in time, over a great length 

 of the conductor. 



