342 > PHILOSOPHICAL TRANSACTIONS. [aNN0 1778. 



Exp. 7. When the Sd experiment was repeated, and with the same number 

 of turns, the sensation was observed to be full as violent as if no such metallic 

 interposition had been presented to it. — Exp. 8. On repeating the 4th experi- 

 ment, and with 1 turns of the wheel also, the sensation was not near so con- 

 siderable ; for it seemed something less than what was experienced with the long 

 rounded conductor in the 6th experiment. < r 



3d Observation. — The several effects observed in the last 4 experiments agree- 

 ing so exactly with those in the first 4, prove, at least so far, that rounded ends, 

 in these cases, received the fluid less readily, and in less quantity, than points. 



Exp. Q. In the 1st experiment (when the long pointed conductor was put 

 upon the model, and while the wheel was turning) a very small spark might be 

 taken from the short spout ; but if the hand, or a wire, was applied, which 

 communicated with the well, and continued in contact with the short spout, or 

 if it was connected with the long spout, the small stream of light seen before at 

 the top of that spout now ceased. — Exp. 10. But this was not the case when the 

 3d experiment was repeated (that is, with the short rounded conductor) ; for 

 this, by reason of its greater distance from the cylinder, and the nature of its 

 termination, did not draw a sufficient quantity of the charge from the great 

 cylinder to cause the least appearance of a stream of light, as in the former 

 case. — Exp. 1 1 . The effect however was different when a pointed conductor, of 

 the same length as in the 4th experiment, was made use of; for then the short 

 spout was charged nearly in the same manner as in the 1st experiment, and the 

 stream of light at the top of the bent spout disappeared the instant a communi- 

 cation was made from the short spout to the earth. 



4th Observation. — The 2 posts of wood on the ground, which supported 

 the cistern at the bottom of the short spout, were therefore the true cause of 

 these efKicts taking place in the short spout, by preventing a communication with 

 the earth, and hindering the fluid, that was constantly charging the short 

 spout, from discharging itself properly into the earth. 



Exp. 12. The model (furnished with the wire of communication, and with 

 the longest pointed conductor on it) being properly placed on the long frame, 

 and held there in readiness to be drawn forward by the line and weight at the 

 other end ; the great cylinder was charged by 20 turns of the wheel. On letting 

 go the model, and almost at the instant before the point came under the centre 

 of the cylinder, it was suddenly struck with the matter of lightning, and fre- 

 quently sooner. The least distance of the point from the great cylinder, when 

 this stroke happened, measured nearly 5 inches. The quantity of charge that 

 remained in the cylinder was very little to the sense of feeling, though taken 

 immediately after the stroke liappencd. — Exp. 13. On putting into the place of 

 . the pointed conductor one of tlie same Icugtii, that was rounded at the end, and 



