436 PHILOSOPHICAL TRANSACTIONS. [aNNO 1778. 



it now struck with a very small spark to the point, the point depriving the 

 moveable cloud of most of its electricity as it approached it, which was very 

 visibly passing away between the separations of the tin-foil. 



Exp. 12. Every thing as in the last experiment, a chain only being hung on 

 the pointed wire, to complete the metallic communication with the earth. As 

 soon as the chain was hung on, the moveable artificial cloud instantly ceased 

 striking to the point, and the other end of it was then attracted to the artificial 

 cloud, which then kept constantly striking to it: the moveable artificial cloud 

 did not return to the point as it did before the chain was hung on, as in the last 

 experiment. 



Observation. — In the 18th experiment, where the moveable artificial cloud 

 was intended to represent a cloud in its natural state receiving electric fire from a 

 charged cloud, we find, that the point deprived it of its electric fire which it 

 received from the charged one so fast, that the artificial cloud could keep con- 

 stantly striking to the other end, without repelling it from it; but that in the 

 19th experiment, when the ball was under the end of the moveable artificial 

 cloud instead of the point; then, instead of the artificial cloud continuing to 

 strike to the other end without repelling that end, it now first attracted and 

 charged it with electricity, or the matter of lightning; then immediately repelled 

 it, and being attracted by the ball under the other end, it moved down with an 

 acquired velocity, till it came within its striking distance, discharging then its 

 electricity on the ball with a loud and strong spark, and so continued alternately 

 receiving and discharging its electric fire on the ball. It being first attracted, at 

 which time it received an additional quantity of electricity, and then repelled till 

 it had discharged that additional quantity, is exactly agreeable to all the known 

 laws of electricity. 



This experiment may throw some light on what we sometimes see in 

 nature, viz. one cloud continuing to strike towards the earth a considerable time ; 

 for should a cloud in its natural state be so situated between a charged cloud and 

 the earth, it may be first attracted and charged, and then repelled, and if it 

 should be repelled so as to come within the attracting distance of any blunt body 

 with a good or partial conductor, it would then continue to be attracted till it 

 came within its striking distance, and then discharge its lightning suddenly on 

 it; and if it was not repelled or attracted beyond the attracting distance of the 

 charged cloud, it would again be attracted to it and charged, then repelled as 

 before, and so may continue receiving and discharging the lightning, till the 

 charged cloud is nearly exiiaustedof its electricity or matter of lightning. 



But if a cloud, in its natural state, should be so situated within the striking 

 distance of a charged cloud, and at the same time within the power of a good 

 metallic conductor terminating in a point; then from these experiments it 



