Mr. C. Toinlinson's Experiments on the Electrical Fly. 217 



the shoulder ceases to be heard, and the action is now between 

 the + flame and the + knobs. A point held near the fly has 

 a similar action to that of the flame, and also conducting vapours 

 such as ether, &c. 



The conducting action of flame is well shown in the following 

 experiment. A metal-pointed stand, connected by a chain with 

 the prime conductor, was placed in the centre of a dessert plate 

 in which were put some coils of lamp-cotton wetted with spirits 

 of wine. The fly on the point spun with great rapidity when 

 the machiue was worked; but when the spirit was kindled the 

 fly stopped, and did not begin to spin again until the flame had 

 died out. 



7. Conclusion. 



A cork playing on the surface of a liquid dielectric between 

 two oppositely electrified wires, I have already compared with 

 the dancing figures and'pith-balls, and the electric pendulum. 

 In the electric pendulum, a pith-ball or other light object is 

 suspended between the knobs of two Leyden jars differently 

 electrified. The ball is attracted by one knob, and is similarly 

 electrified and then repelled ; or what is the same thing, it is 

 attracted by the other knob, by which it is discharged, similarly 

 electrified, and then repelled, and in this way a rapid action is 

 kept up, the ball describing various kinds of curved figures 

 between and around the two knobs, sometimes striking them with 

 a smart blow such as can be heard all over the room — at other 

 times not touching them, but parting with its charge to the 

 electrified particles of air which, like itself, we must suppose 

 are being similarly attracted and repelled by the two excited 

 knobs. That is, the particles of air as they leave either knob 

 being charged, say -f-, encounter the pith-ball electrified, say — , 

 and combine with its electricity in proportional quantities to 

 neutralize it and themselves ; but as there are myriads of parti- 

 cles leaving the + knob, they take the place of the neutralized 

 particles, and communicate a plus charge to the pith-ball before 

 it has time to reach the brass knob, so that it is actually in a 

 condition to be repelled by the -f knob and attracted by the 

 — knob without touching either. The rapid whirling motion 

 of the pith-ball in air and of the cork in paraffin oil, &c, must, 

 I suppose, represent what takes place among the particles of air 

 and the particles of the liquid dielectric ; but there is this differ- 

 ence between the two media. Introduce an uninsulated point, 

 free to move, into polarized air, and convective discharge sets in 

 upon and in the direction of that point ; the particles become 

 similarly electrified to the point, and repulsion takes place with 

 sufficient force to cause the point to move backwards. In a 



