Thus the assumption which we have made, that there is some process in nature in virtue of which, opposite to any twist, its image twist is produced as a real thing—this assumption is in harmony with the laws of induction. Instead of working with a glass rod it is more convenient to use a metal rod. Suppose we take a poker and attach a handle of sealing wax to its middle. See A B below. This will be easily imagined, and its two ends, the handle and the black end, will be easily retained in the mind. If now electricity be communicated from the glass rod to the poker by touching the two together, what happens is this: The particles of the glass being twisted communicate their twist to the particles of the poker. The twist on the poker is of the same kind as the twist on the glass rod, and the amount of twisting which the glass particles had is divided between the glass rod and the poker. The use of the sealing-wax handle is to keep the twist from communicating itself to the body of the person holding it, and, through him, to the earth. It is found that certain bodies, “non-conductors,” will not communicate the twist and convey it along; whereas metallic bodies, and conductors generally, will communicate this twist at once to great distances. We will suppose that a metallic body consists of particles so arranged together that it easily acts as a set of minute threads or chains of particles which will twist, each thread or chain twisting as a whole. Thus the conception which should be formed of a metallic body conducting electricity along it is this:—Conceive a bundle of very fine but very rigid wires, each wire twisting separately but with the same kind of twist as all the others, and each, as it twists, rotating amongst its fellow threads. If we have a metal rod we can twist it between the finger and thumb. This is not the kind of twist we suppose, but that each separate string of particles is thus twisted, so that each set twisting remains in the same part of the metal rod—but is turning round in its fixed position. This is a body conveying an electric current. If the current will not pass, the set of minute wires must be conceived as held at the far end, and given a twist, starting from the point where the electricity is communicated. Now if a conductor is thus charged and left, it is found that it retains its charge; to be discharged it must be touched with another conductor. Hence this twist of minute threads differs from a twist of a wire in that the threads cannot untwist of themselves unless other threads come into contact with them to which they can impart the twist. That this should be the case may depend on the fact that the twisting strings are strings of molecules, and the ends of them would thus be connected with other molecules with something of the same tenacity as that with which the strings themselves cohere together, and are unable to unlock themselves from these insulating or untwisting molecules.