VOL. LXVIII.] PHILOSOPHICAL TRANSACTIONS. 351 



Exp. 41. When the great cylinder and wire with the drums were fully 

 charged, and a person, standing on the wire which communicated with the well, 

 suddenly approached the brass drums with his hand, an explosion ensued, wiiich 

 indeed was neither so large, nor did it take place at so great a distance, as might 

 have been expected; yet the person received a violent sensation, not unlike that 

 produced by the Leyden phial, as it affected his body quite through, from the 

 hand that took the discharge to the feet that stood on the wire. — Exp. 42. On 

 repeating the above experiment, with the great cylinder only, and when it was 

 fully charged, the explosion appeared stronger, and the distance it struck at 

 greater, than in the other case; and yet the sensation received was not near so 

 violent as when the long wire was connected with it. — Exp. 43. When the little 

 cylinder by itself was fully charged, the effects were very inconsiderable, com- 

 pared with those from the great cylinder: for, in this case, the person standing 

 on the wire of communication was affected in his hand only, and that no farther 

 than the wrist. 



\Tth Observation. — ^When all the circumstances in the last two experiments 

 are considered, we may safely conclude, that the difference in the sensation, pro- 

 duced by the two cylinders, could arise from no other cause than a difference in 

 their lengths; the one being 14 times longer than the other, and both in other 

 respects nearly similar; and since the sensation perceived in the 38th experi- 

 ment, where the long wire was employed, was considerably greater than when 

 the great cylinder alone was charged, we seem to have sufficient reason to appre- 

 hend that the effects of every charge, as to sensation, will be proportional to 

 the length of the body charged; provided the charge be uniform from end to 

 end in every experiment. Apprehending that, if some of the circumstances 

 employed in producing the charge were varied, we might possibly obtain a 

 greater charge than we had yet found, I made the following experiments. 



Exp. 44. Instead of one machine to charge the great apparatus, I made use 

 of two. The glass cylinders belonging to each were of the same length and 

 diameter nearly. One of those machines was continued in its usual place, which 

 was not far from the nearer end of the great cylinder. The other stood at the 

 farther end of the brass drums. After connecting the long wire with the great 

 cylinder and brass drums, in the manner before described, the wheels of both 

 machines were put into motion, with equal and uniform velocities: and after six 

 turns of each wheel, and waiting above 8 seconds, a person suddenly approached 

 the brass drums with his hand; immediately an explosion took place, and a 

 disagreeable sensation was perceived. The discharge was then made at the 

 nearer end of the great cylinder, and there seemed to be no difference in the 

 effect. 



Exp. 45. On repeating the experiment with one machine only, and after 



