VOL. LXIV.] PHILOSOPHICAL TRANSACTIONS. 559 



If the plate of glass be placed in a frame of wood, and a light pith or cork 

 ball be laid on its surface, on presenting towards it the end of a finger, or the 

 point of a pin, &c. the ball will recede from them, with a very brisk motion, 

 and may thus l)e driven about on the surface of the glass, like a feather in the 

 air, by an excited tube, or the wire of a charged bottle. The cork-ball, being 

 deprived of its electricity by the pin, &c. instantly flies to that part of the glass 

 to which it is attracted the most forcibly. ) 



Exper. 3. I hung on the prime conductor a small phial, 2 inches in diameter, 

 coated 3^ inches from the bottom. From the coating of this phial I suspended 

 1 chains: the first in contact with a heavy weight, placed on a card, across 

 which I had ruled lines at equal distances, fig. 10, the 2d chain formed a circuit, 

 with leaden pipe, small brass wire, small chain, &c. of 120 feet in length 

 From the ball of the discharging rod, which rested on another weight, I also 

 hung a chain, in contact with, and completing the circuit of ] 20 feet before- 

 mentioned ; and observed, that if the bottle was charged quite full, the electri- 

 city would, in the discharge, pass through the long circuit, rather than over the 

 surface of the card, when the weights were placed at -V of an inch asunder ; but 

 if I charged the bottle only about half full, the electricity would, in the dis- 

 charge, pass through the long circuit, rather than over the surface of the card, 

 though the weights were placed at the distance of only -j-V of an inch. Query, 

 Can there be a greater proof of the small resistance made by metal to the passing 

 of the electric matter, compared with card, wood, &c. and consequently of the 

 utility of metallic conductors to buildings, ships, &c. ? The same observation 

 has been repeatedly made, on the effects of the natural electricity. 



Exper. 4. Having prepared a phial, in the manner directed by Mr. Lane, for 

 making his curious experiment, by passing a wire through the bottom, and an- 

 , other through the cork, so as to bring the ends of the 2 within half an inch of 

 each other, about the middle of the bottle, which was filled with water, I found, 

 as that gentleman observed, that a slight shock of electricity discharged through 

 it, would break the bottle. But having put a very small wire from the top to 

 the bottom of it, through the water; I discharged through it 3 large jars, con- 

 taining l6 square feet of coated surface, when the whole of the smiill wire was 

 exploded; but the bottle remained unhurt. If therefore a metallic conductor, 

 being too small, should happen to be destroyed by a stroke of lightning, yet the 

 building, &c. to which it is afiixed, will probably escape uninjural. j 



Exper. 5. When I strongly electrify a large prime conductor, 3 feet long, and 

 12 inches in diameter, if a person hold in his hand a brass rod terminated by a 

 ball, 2 inches in diameter, at the distance of 2 inches from the side of the con- 

 ductor, fig. 11, he will continue to draw such strong sparks as will give him a 

 sensible shock in both his legs ; but if another person at the same time present 



