ELECTRICITY. 831 



Of the influence of Points in Electricity. 



AVhen a conducting body is made of a pointed 

 form it easily parts with its electricity, and ac- 

 quires it more easily from another. This is ren- 

 dered very obvious, if the experiments are made 

 in the dark. If a sharp pointed wire be fixed upon 

 the prime conductor while the machine is in action, 

 the electric matter will be seen issuing from it in 

 the form of a pencil or brush, and of a beautiful 

 bluish colour, and with a kind of rustling noise. 

 But if the wire be held in the hand, and presented 

 to the prime conductor, a brilliant star will be seen 

 upon the point of it, owing to the entrance of 

 the electricity into the point which draws it from 

 the conductor. 



If a plate of tin be cut into the form of a star 

 (Fig. 7-)' ail( ^ De supported on its centre by a wire 

 projecting from the prime conductor, as soon as 

 the wheel of the machine is turned, and this appa- 

 ratus electrified, a flame will appear at the extre- 

 mity of every angle of the star, which will be very 

 beautiful ; and if the star be made to turn swiftly 

 on its centre, an entire circle of fire w T ill be seen in 

 the dark. This experiment will be more surpriz- 

 ing, if the operator now and then privately touch 

 the prime conductor, as by this means he may 

 command the appearance or disappearance of the 

 star, or circle of fire, at pleasure. 



If two sharp-pointed wires be bent (Fig. 8.), 

 with the four ends at right angles, in the same 

 plane, but pointing different ways, and be made to 

 turn upon the point of wire fixed in the prime 

 conductor \ the moment it is electrified, a flame 

 will be seen at the points a, b, c, d ; and the wire* 



