The possibility of making a record of animate movement, and subsequently reproducing it, was predicted long before the actual accomplishment. This, as we have seen, was also the case with the phonograph, the telephone, and the electric light. As to the phonograph, the prediction went only so far as the RESULT; the apparent intricacy of the problem being so great that the MEANS for accomplishing the desired end were seemingly beyond the grasp of the imagination or the mastery of invention.

With the electric light and the telephone the prediction included not only the result to be accomplished, but, in a rough and general way, the mechanism itself; that is to say, long before a single sound was intelligibly transmitted it was recognized that such a thing might be done by causing a diaphragm, vibrated by original sounds, to communicate its movements to a distant diaphragm by a suitably controlled electric current. In the case of the electric light, the heating of a conductor to incandescence in a highly rarefied atmosphere was suggested as a scheme of illumination long before its actual accomplishment, and in fact before the production of a suitable generator for delivering electric current in a satisfactory and economical manner.