VOL. LXVIII.] PHILOSOPHICAL TRANSACTIONS. 433 



communication with moist earth ; and from all the accounts he had met with, 

 this seems to have been the cause of their having been struck. From the 12th 

 experiment we learn, that a very fine wire will conduct a strong spark. 



Mr. N. contrived another moveable artificial cloud: it consisted of a hollow 

 tube of wood, with a ball at each end, being together about 6 feet in length: 

 from each end was suspended a light hollow wooden cylinder; these with the 

 balls and tube were covered with tin-foil: it was placed with its axis resting on 

 two semi-circular hollows in a piece of brass fixed on a glass pillar, by which it 

 was insulated: it moved very easily on its axis, and was brought to a horizontal 

 position by means of two moveable pieces. 



Exp. 13. Mr. N. first put this moveable artificial cloud into a horizontal posi- 

 tion, and placed it so that the brass on which the axis rested, was in contact with 

 the end of the artificial cloud. Then, under each of the hollow cylinders he placed 

 a stand, having a good metallic communication with the earth. On one of the 

 stands was put a pointed wire, the same as was used in the 4th experiment; and 

 on the other, a brass ball of 3 inches diameter. He then placed the point and 

 ball each 12 inches from the middle of the bottom of its correspondent hollow 

 cylinder: on charging the artificial cloud (which consequently charged the move- 

 able artificial cloud in contact with it) the point was luminous, and the moveable 

 artificial cloud still remained in a horizontal position, though there was now a 

 point under one end and a ball under the other; and on ceasing to charge the 

 two clouds, it was found directly after, that the point had drawn off almost all 

 the electric fire from both. 



Exp. 14. The two clouds being charged, he took away the stand with the 3 

 inch ball on it : the point remained luminous, and the moveable artificial cloud 

 still continued horizontal, not being attracted to the point, though there was 

 now only the stand with the pointed wire under one end of it, the point having 

 carried off" the electric fire as in the last experiment. 



Exp. 15. The two clouds being again charged, he replaced the stand with 

 the ball on it; and now, instead of taking away this stand, as he did in the last 

 experiment, he took away the stand with the pointed wire on it: the consequence 

 was, that the end of the moveable artificial cloud was now attracted down to the 

 ball till it came to its striking distance, where it then discharged its electricity 

 on it in a strong spark. The moveable artificial cloud then receded a little till 

 it was charged, and then was attracted by the ball as before, till it came to its 

 striking distance, when it again discharged its electricity at once, and so con- 

 tinued striking and then receding to a little distance as long as the two clouds 

 were charged. 



Exp. l6. The moveable artificial cloud continuing to strike to the ball as in 

 the last experiment, he now replaced the stand with the pointed wire on it, then 



VOL. xi»'. 3 K 



