VOL. LXIV.] PHILOSOPHICAL TBANSACTIONS. 535 



tween 2 brass balls, a and b, about 2 inches asunder ; properly introduced into 

 the circuit, fig. 8. Then having given a small phial 2 or 3 turns of the globe, 

 charging it positively, connect the coating of it, by a chain, with the wire of 

 the ball a ; and on applying the knob of the phial, to the wire of the ball B, 

 you will observe the flame to be plainly driven from it ; being often blown upon 

 the ball a, so as to blacken it with the smoke. Then charge the phial 

 negatively, and, the apparatus remaining as before, apply the knob of the phial 

 as at first ; and you will then perceive the flame to be blown quite in the contrary 

 direction, viz. from a towards, and often upon b, as on Dr. Franklin's princi- 

 ples of the Leyden bottle, it ought to bcMii rtu h '■ ,inU\, 



Exper. 2. Charge a large jar positively, and insulate it ; then take a long 

 curved wire, pointed at both ends, and hold it by a glass handle, so as to bring 

 one end of the wire half an inch from the knob, and the other end of it to the 

 same distance from the coating of the jar. You will then observe a small lumi- 

 nous spark on the point opposed to the knob of the jar, and a fine pencil, 

 diverging from the lower point, spreading on the coating of the jar, which will 

 presently discharge it silently. Then charge the jar negatively ; insulate it, and 

 apply the wire as before ; and the appearances at the points of the wire will be 

 directly reversed ; plainly demonstrating the direction of the electricity in the 

 discharge of the bottle. 



Another very convenient and easy method, of exhibiting the phenomena of 

 the positive and negative electricity of the inside and outside surfaces, of a 

 charged Leyden bottle, is by slipping a cap of metal, furnished with a ball and 

 wire, on the outside coating ; and mounting it on an electric stand, in a 

 horizontal position, as fig. 12; or if the bottom of the glass be turned much 

 upward into the body of it, a piece of wood may be worked to its shape, and 

 cemented to it ; then through the middle of this wood, a short tube of metal 

 may be inserted, so as to admit the wire which is connected with the ball to pass 

 through it ; and be brought into contact with the coating of the jar, at pleasure. 

 By this means, experiments may be made, at either end of the bottle, with great 

 facility ; and other charged or exhausted bottles, excited ribbons, or other elec- 

 trics : the curved pointed wire, &c. &c. may be readily applied ; and give or re-i 

 ceive a spark ; be attracted or repelled ; according to the kind of electricity in 

 the two bodies so applied towards each other. By hanging a chain round either 

 of the wires, and connecting it with one end of the discharging rod ; and bring- 

 ing the other end of the rod so as to leave a proper space between that and the 

 ball on the wire, at the opposite end of the bottle ; the flame of a taper, &c. 

 may be interposed, and show the direction of the electricity in the discharge : 

 or a cork-ball, hung by silk, may play between them, in the manner described 

 by Dr. Franklin. If the balls are taken off from the wires of the bottle, the 



4 b2 



