Page:Popular Science Monthly Volume 49.djvu/235

Rh the pouch for a stage of its journey, a carrier might come to the end of his trip utterly fagged out; but if ho had barely the strength to pass his burden to the next man it was enough. Much the same is the system of relays when a telegram takes its way from New York to Tacoma. First it goes to Buffalo, where the current, faint after its run of four hundred and forty miles, touches off a second powerful current born in Buffalo. This in its turn bears the dispatch to Chicago. There a third current is impressed into service, and so on, until at the end of a succession of transfers the words are clicked out in Tacoma. This whole process is committed to self-acting repeaters that do their work in the fraction of a second. It is in pulling triggers in such fashion as this, in liberating forces indefinitely greater than the initial impulse, that electricity brings to muscles of brass and steel something very like a nervous system, so that the merest touch directs the course of a steamship through the tempest-tossed Atlantic. Engineer, workman, and artist can thus reserve their strength for tasks more profitable than muscular dead lift and find their sweep of initiation and control broadened to the utmost bound. In the field of war, for instance, a torpedo can be launched, propelled, steered, and exploded by a telegraph key a mile or two away; the constructor may, indeed, confidently give all his orders in advance and build a torpedo which will fulfill a fate of both murder and suicide predestined in its cams and magnets. Or a camera, under the control of an operator at the safe end of a wire, is sent soaring in a balloon car above an enemy's camp, effectively playing the spy.

Another apparatus electric and photographic, happily less uncommon, is employed for observatory records which, as near Arequipa, in Peru, without supervision keeps itself busy for a fortnight together. Still more remarkable is Mr. Muybridge's round of cameras, timed as only electricity can time them, which seize practically instantaneous views of figures in rapid motion, as horses trotting. In Mr. Edison's kinetoscope photographs made at each forty-sixth of a second follow one another so quickly under an eyepiece as to fuse with the effect of life and action. Pictures of birds thus caught on the wing may prove seed corn for harvests to be reaped by the experimenter in mechanical flight—an achievement which, strange to say, attracts the interest of military rather than business men. In the service of war and peace one would suppose the ordinary telegraph to be speedy enough. Not so, thinks the inventor. In the latest process a dispatch wings its way from New York to Chicago at the rate of one thousand words a minute, to Philadelphia thrice as fast. The telegram is taken first to a machine which symbolizes each letter as perforations on a strip of paper; then the strip is run between.