VOL. LXVIII.3 PHILOSOPHICAL TRANSACTIONS. 435 



artificial cloud, and placed it, together with the glass pillar by which it was insu- 

 lated, on another foot of such a height that when the ball at one of the ends was 

 3 inches above the ball c at the end of the artificial cloud, then the moveable 

 artificial cloud was horizontal. He then placed the stand with the point at the 

 distance of ] 8 inches, and directly under the ball at the other end : on charging 

 the artificial cloud, the point was luminous; and that end of the moveable 

 artificial cloud which was 3 inches above the ball c was attracted down to it, then 

 receded from it about 1 inch, and then the artificial cloud kept constantly 

 striking to it, as long as it continued to be charged. On ceasing to charge the 

 artificial cloud, it was found immediately after, that the point had carried off" 

 almost all the electric fire. 



Exp. 19. Every thing remaining as in the last experiment, and the artificial 

 cloud being charged, Mr. N. took away the stand with the point, and placed in 

 its stead the stand with the 3 inch bull on it, exactly at the same distance as the 

 point: then instantly that end of the moveable artificial cloud, which had con- 

 tinued to be attracted down near to the artificial cloud, was repelled from it, and 

 at the same time the other end was attracted by the 3 inch ball, till it came so 

 near as to discharge its electricity on it in a strong spark. The end of the 

 moveable artificial cloud then receded from the 3 inch ball, the other end being 

 now attracted by the artificial cloud, which charged it almost instantly again; it 

 then receded with rapidity from it, and discharged its electric fire on the ball as 

 before, and thus continued in great motion receiving strong sparks from the 

 artificial cloud, and discharging them on the ball, representing in miniature a 

 storm of lightning where an electrical cloud strikes into another cloud, and that 

 discharges itself on a building which is without a regular conductor, or one ter- 

 minating with a ball. 



Exp. 10. While this storm of lightning in miniature continued, Mr. N. 

 removed the stand with the 3 inch ball, and placed in its stead the stand ter- 

 minating with the point; the point was immediately luminous, and in an instant 

 the artificial storm ceased. The end of the moveable artificial cloud, next 

 the charged artificial one, was now attracted to it, as in the 18th experiment. 



Exp. 21. The apparatus remaining as in the last experiment, Mr. N. 

 unscrewed the pointed wire from the stand, and screwed it into one end of a 

 stick of wax of 6 inches in length, with 11 pieces of tin-foil stuck on it at the 

 40th part of an inch asunder; he then screwed this wax with the point on the 

 stand, and placed it so that the point was directly under the end of the moveable 

 artificial cloud, and at 18 inches distance as before: on charging the artificial 

 cloud, the moveable artificial cloud was first attracted, then repelled, and so 

 alternately as when the stand with the 3 inch ball was under; but with this dif- 

 ference, that instead of striking in a strong spark, as it did to the 3 inch ball, 



3K 2 



