Page:Popular Science Monthly Volume 39.djvu/133

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mained unexplored. Even in our own century, what a long gap there was between the first production of the electric light and its application to practical purposes! It all seems very plain now, but two generations had to elapse before the electric light, as produced by Sir Humphry Davy in 1808, became available for general use. But if the progress made by electrical science was slow in its earlier stages, amends are truly being made now in the rapidity with which new views and new applications of electricity are crowding upon the world. The alleged miracles of olden time seem poor and commonplace in comparison with the miracles wrought by a little accurate knowledge. Here we have a power that has been in the world from the beginning, but from which, down to the present century, not one single valuable result was drawn, for the simple reason that we, or our predecessors, did not know how to use it, did not even know enough to recognize it in some of its manifestations. To-day, mankind has no more obedient, or, it may be added, capable servant. The early students of electricity had a task that closely resembled putting together a complicated puzzle of which there was no plan; but, as piece was joined to piece, the plan began to reveal itself, and subsequent progress was rapid. To-day, if the puzzle is not complete, at least we have, as far as it goes, a very symmetrical and intelligible pattern before our eyes.

It would be vain to attempt, within the limits of a brief article like the present, to give even a catalogue of the various applications of electricity now in daily use. Like chemistry, electricity has undergone a process of subdivision, and no one man can pretend to keep abreast of the latest developments in all its branches. The year 1837 saw the first telegraph for practical business purposes, and from that time to this there has been a constant stream of improvements in the methods and appliances of the telegraphic art. The whole world is girdled round and round with lines quivering with the impulses that translate the thoughts of men. Enormous as has been the extension of telegraph lines, well-nigh a million miles being now in use in this country alone, they would be utterly inadequate to the needs of the community but for the improvements that have been made in the way of duplex and multiplex telegraphy. The whole business of the world has adapted itself to the changed conditions which the telegraph has introduced. Without the telegraph the railway would be shorn of far more than half its efficiency, and the press of even metropolitan cities would shrink to provincial dimensions. It is becoming difficult to conceive what the state of business would be without even the telephone, which, in every large city, does the work of a whole army of messenger boys. How little we think of electricity when we press the button that closes an electric circuit and rings a bell 1 Yet the electric bell is certainly one of the most convenient of so-called modern improvements. Without it our great hotels, our public offices, our monster steamships would be much more difficult of management. Our signal service depends upon electricity to outrun the swiftest blasts of storm and herald their approach. The observations of the astronomer would lose much in precision were it not for the simple yet admirable instrument known as the chronograph. For all purposes of instantaneous registration, there is nothing equal to the action of electricity, the velocity of which is equivalent to that of light itself, and its applications for this purpose must go on increasing in number from year to year. Even as it is they are legion.

The electric light would seem to have furnished the world with the final and definitive source of illumination. It is not twenty years since even so good an authority as Prof. Tyndall spoke doubt-