There are in the United States new applications of electricity literally every day. Before the written page is printed some startling application is likely to be made that gives to that page at once an incompleteness it is impossible to guard against or avoid. There is a strong inclination to prophesy; to tell of that which is to come; to picture the warmed and illuminated future, smokeless and odorless, and the homes in which the children of the near future shall be reared. Some of those few apprehended things, suggested as being possible or desirable in these chapters, have been since done and the author has seen them. This American facility of electrical invention has one great cause, one specific reason for its fruitfulness. It is because so many acute minds have mastered the simple laws of electrical action. This knowledge not only fosters intelligent and fruitful experiment but it prevents the doing of foolish things. No man who has acquired a knowledge of mechanical forces, who understands at least that great law that for all force exerted there is exacted an equivalent, ever dreams upon the folly of the perpetual motion. In like manner does a knowledge, purely theoretical, of the laws of electricity prevent that waste of time in gropings and dreams of which the story of science and the long human struggle in all ages and in all departments is full.
Finally, I would, if possible dispell all ideas of strangeness and mystery and semi-miracle as connected with electrical phenomena. There is no mystery; above all, there is no caprice. There are, in electricity and in all other departments of science, still many things undiscovered.
It is certain that causes lead far back into that realm which is beyond present human investigation. _Force_ has innumerable manifestations that are visible, that are understood, that are controlled. Its _origin_ is behind the veil. A thousand branching threads of argument may be taken up and woven into the single strand that leads into the unknown. Out of the thought that is born of things has already arisen a new conception of the universe, and of the Eternal Mind who is its master. Among these things, these daily manifestations of a seeming mystery, the most splendid are the phenomena of electricity. They court the human understanding and offer a continual challenge to that faculty which alone distinguishes humanity from the beasts. The a.s.sistance given in the preceding pages toward a clear understanding of the reason why, so far as known, is perhaps inadequate, but is an attempt offered for what of interest or value may be found.