52 Additional Notes. 



electricity is accumulated, the accumulated electricity will pass off at 

 a much greater distance than if a metallic knob be fixed on the wire 

 and presented in its stead. 



2. The same occurs if the metallic point be fixed on the electrised 

 conductor, and the finger of a person standing on the ground be pre- 

 sented to it, the accumulated electricity will pass oft" at a much greater 

 distance, and indeed will soon discharge itself by communicating the 

 accumulated electricity to the atmosphere. 



3. If a metallic point be fixed on the prime conductor, and the 

 flame of a candle be presented to it, on electrising the conductor either 

 with vitreous or resinous ether, the flame of the candle is blown from 

 the point, which must be owing to the electric fluid in its passage 

 from the point carrying along with it a stream of atmospheric air. 



The manner in which the accumulated electricity so readily passes 

 off by a metallic point may be thus understood; when a metallic point 

 stands erect from an electrised metallic plane, the accumulated elec- 

 tricity which exists on the extremity of the point, is attracted less 

 than that on the other parts of the electrised surface. For the particle 

 of electric matter immediately over the point is attracted by that 

 point only, whereas the particles of electric matter over every other 

 part of the electrised plane, is not only attracted by the parts of the 

 plane immediately under them, but also laterally by the circumjacent 

 parts of it; whence the accumulated electric fluid is pushed off at this 

 point by that over the other parts being more strongly attracted to 

 the plane. 



Thus if a light insulated horizontal fly be constructed of wire with 

 points fixed as tangents to the circle, it Avill revolve the way contrary 

 to the direction of the points as long as it continues to be electrised. 

 For the same reason as when a circle of cork, with a point of the cork 

 standing from it like a tangent, is smeared with oil, and thrown upon 

 a lake, it will continue to revolve backwards in respect to the direc- 

 tion of the point till all the oil is dispersed upon the lake, as first 

 observed by Dr. Franklin; for the oil being attracted to all the other 

 parts of the cork-circle more than towards the pointed tangent, that 

 part over the point is pushed off and diffuses itself on the water, over 

 which it passes Avithout touching, and consequently without friction; 

 and thus the cork revolves in the contrary direction. 



