the drawing do not touch, one is shown as going round it in a little half-circle. This is the usual method used in electrical diagrams of showing that two wires cross without touching. Owing to the metallic connection established by these wires, the potential of A is always the same as the potential of a. Similarly B and b are at the same potential. Into the middle of each cylinder there is carried the discharge nozzle of a water pipe, and the flow of water is regulated by means of a stopcock in such manner that there shall be no continuous stream, but a succession of drops.
The drawing is only diagrammatic, and does not represent the actual shape of the parts. In conductors intended for the accumulation of a charge, all sharp corners must be avoided so as to minimise dispersion of charge, which is strongest the smaller the radius of curvature. Any corner is in reality a curved surface, but with a very small radius of curvature. The different parts of a charge distributed over any surface repel each other. If the surface is quite plane the repelling force between the elementary particles of the charge is parallel to the surface, and there is no component tending to flake electricity off the surface and disperse it into the air. If the
