VOL. LXVIII.] PHILOSOPHICAL TRANSACTIONS. 431 



also removed the other stand with the ball, to which the artificial cloud likewise 

 struck, in the same experiment; the artificial cloud was then charged, and the 

 stand being placed in such a manner that the point was directly opposite to the 

 side of the artificial cloud; it was then removed till he found the distance at 

 which the light between the separation of the tin-foil no longer became visible. 

 This distance of the point on the wax was above 7 feet, how much farther it 

 might have been luminous he had no opportunity of trying, this distance being 

 the farthest he could remove it in his room, and under the disadvantage of 

 having the end of the artificial cloud within 33 inches of the edge of the wain- 

 scot. When a ball of -^ of an inch was put in the place of the point, the 

 light was visible at the distance of 4^ feet, but with a ball of 3 inches diameter 

 only at 2 feet. 



Exp. 10. Mr. N. took another stick of sealing-wax, l-p\ inch diameter, and 

 about 10 inches long, and pasted on it round pieces of tin-foil of half an inch in 

 diameter, at about half an inch distance from each other. One end of this 

 stick of wax was screwed to the receiving rod, d; and into the other end was 

 screwed the pointed wire used in the 4th experiment. He then laid a piece of 

 brass on this wax, so as to connect all the separations of the round pieces of 

 tin-foil except 2; then the point of this wire on the wax was placed nearly in 

 contact with the ball. On charging the artificial cloud the electric fire now 

 struck to the point, and continued to strike to it all the while it was gradually 

 removed to the distance of l-^ inch: beyond that distance it would not strike, 

 but the point continued luminous till it was removed to the distance of 3 feet. 



Exper. 11. The apparatus remaining as in the last experiment, he only took 

 away the piece of brass which laid on the wax to connect the pieces of tin-foil toge- 

 ther. The charged artificial cloud did not now strike to the point till it was removed 

 from the ball c to the distance of 4-i- inches; it then began to strike to it, and 

 continued striking while it was gradually removing sometimes to 10 inches; but 

 when the point was removed beyond the greatest striking distance, the point was 

 not luminous as in the last experiment, except when the artificial cloud dis- 

 charged its electric fire out into the air, in a diverging pencil from the ball c : it 

 was then luminous, but at that instant only. Every time the artificial cloud 

 struck to the point, the electric fire made a beautiful appearance in passing off 

 between the separation of the pieces of tin-foil. Mr. N. then connected all the 

 tin-foil on the wax, so as to leave no separation ; then the charged artificial 

 cloud would not strike to the point at any distance. 



Exp. 12. Mr. N. placed the rod d, with the 4 inch ball at the end as in the 

 first experiment, this he put on a glass pillar to insulate it; then from the rod he 

 made a communication to the earth, with about 3 feet of silver wire, which was 



