Observations on some Experiments in Electricity. 59 



city. The rods of a Henley's discharger were employed to connect 

 the positive and negative ends of the revolving machine. Between 

 the balls was placed a card, suspended like a pendulum, wiih its faces 

 to the two balls, and so confined as to prevent its revolving on the 

 suspending rod as an axis, yet having a freedom of vibration, so as 

 to carry its opposite faces successively into contact with the two balls. 

 The suspending rod, as well as the two supports, were of glass. 

 Both wires of the discharger were, as usual, pointed, but provided 

 with balls of different sizes, with which the points could be covered 

 at pleasure. On working the machine while the points were un- 

 covered and the rubber insulated, but the collecting points in com- 

 munication with the ground as well as with the rod of the discharger, 

 it was found that the pendulum was propelled towards the positive 

 or uninsulated point : on covering the negative wire wiih a ball one 

 fourth of an inch in diameter, the card appeared to be undetermined 

 in regard to its direction, but on substituting a ball half an inch in 

 diameter, it was decidedly urged out of its vertical position towards 

 the ball, and on using a still larger ball, of an inch in diameter, 

 the card rose so high as to touch the ball and remain there as long 

 as the machine was in action. On carrying the ball to the opposite 

 wire and leaving the negative uncovered, the card moved still to- 

 wards the ball. Larger balls had the effect of increasing the adhe- 

 sion of the card. When a rapid succession of sparks was transmit- 

 ted through the card, it was frequently observed to maintain a posi- 

 tion nearly stationary between the poles, and this position was found 

 to be the neutral point of the luminous track. A wire a few lines 

 in length, sharpened at both ends and thrust through the paper so as 

 to project on both sides, had the effect to transmit the currents with 

 more steadiness ; but the card was in each case moved the same 

 distance as before from its vertical position. 



3. Flame of a candle between the poles. 



By placing a ball one inch in diameter on the positive pole, and 

 exposing the naked point of the negative one to act upon the flame 

 of a candle, the latter was impelled towards the ball and set fire to 

 a slip of paper wound around it. This proves that the inference 

 formerly deduced from an experiment with two balls, was made 

 without a due regard to all its modifications. By turning the ma- 

 chine very rapidly, the flame was driven entirely away from that side 

 of the wick which was opposite to the pointed (negative) wire and 

 burned only on the side next the ball, reducing the flame to the thick- 



