ii04 Mr. henly’s Experiments and 
rubber may be infulated, and a blunt pointed wire, com- 
municating with the earth, may be placed within half 
an inch of it ; this wire, while the plates are charging, 
will throw off a beautiful pencil of rays diverging upon 
the rubber, and thus compleatly exhibit the progrefs of 
the eleddricity through all the apparatus, from its exit 
out of the earth to its entrance into the earth again : and 
its return may be manifefted by reverfing all the ap- 
pearances upon the points of the wires, in the operation 
of difcharging the glafs lilently by a pointed wire pre- 
sented toward the prime conductor, as above directed. 
Another very fatisfadlory method of demonftrating the 
truth of Dr. franklin’s hypothefis is as follows. I take 
a bottle, containing about one hundred fquare inches of 
coated furface, properly prepared for the Leyden expe- 
riment, and holding it by the wire, I fet the coating upon 
the prime conductor, and charge it negatively (fig. 6.); 
when charged (if not too dry) the upper edge of the 
coating will throw off one or more pencils or brufhes of 
light into the air, which vifibly incline towards the 
charging wire of the bottle, and fometimes actually reach 
it. If I hold the bottle by the coating, andprefent the knob 
to the prime conductor, charging it pofitively (the bottle 
being in a proper ftate) a fmall lpark of light firft appears 
rnpon the edge of the cork in the neckof the bottle, through 
which 
