Many merchants will have their telephonic apparatus fitted with arrangements for setting up type or perforating strips of paper, as already described; and also with receiving apparatus for making the records in typewriting. If they fail to find a subscriber or correspondent on hand at the time when he is wanted, they can write a note to him which he will find hanging on a paper strip from his telephone when he returns. Another mode of accomplishing a somewhat similar result is to provide the telephone receiver itself with a moving strip of steel, which, in its varying degrees of magnetisation, records the spoken words so that they will, at some distance of time, actuate the diaphragm of the receiver and emit spoken words. The degree of permanency which can be attained by this system is, of course, a vital point as regards its practical merits.
Still unsolved electrical problems are the making of a satisfactory alternate current motor suitable for running with the kind of currents generally used for electric lighting purposes—the utilisation of the glow lamp having a partial vacuum or attenuated gas for giving a cheap and soft light somewhat on the principle of the Geissler tube—and last, but not least, the direct conversion of heat into electricity.
With regard to the first-mentioned, the prospects have been materially altered by a discovery announced at the New York meeting of the American Association for the Advancement of Science within a few weeks of the close of the nineteenth century. The handy and effective alternate current motor indeed seemed then as far distant as it had been in 1896, when Sir David Salomons remarked, in his work on Electric Light Installations (vol. ii., p. 97): "No satisfactory alternate current motor available on all circuits exists as yet, although," he added later, "the demand for such an appliance increases daily". It seems, however, that electricians have been looking in the wrong direction for the solution of using the same wire for alternate current lighting and for motive power at the same time. Professor Bedell, of Cornell University, announced at the New York meeting referred to his discovery of the important fact that when direct and alternate currents are sent over the same line each behaves as if the other were not there, and thus the same line can be used for two distinct systems of transmitting electrical energy. No time will be lost in putting this announcement to the test, not only of scientific but also of practical verification, and the probability is that all electric lighting stations in the twentieth century will contain not only dynamos of one type for the supply of light, but also direct current generators for transmitting power in all directions over the same cables.
The glow lamp having no carbon filament, but setting up a bright light with only a fraction of the resistance presented by carbon, would, if perfected, render electric lighting by far the cheapest as well as the best method of illumination. Tentative work has indicated a high degree of probability that success will be achieved, and the glowing bulb is at any rate a possibility of the future which it will be well to reckon with.
In reference to the conversion of heat into electricity without the intervention of machinery to provide motion, and thus to cause magnetic fields to cross one another, very little promise has yet been shown of any fundamental principle upon which a practical apparatus of the kind could be based. The electrician who works at this problem has to begin almost de novo, and his task is an immensely difficult one, although on every ground of analogy success certainly looks possible. In the meantime, as has already been indicated, the steam turbine and dynamo combined, working practically as a single machine for the generation of electricity, offers practically the nearest approach to direct conversion which is yet well in sight.
CHAPTER XI.
WARFARE.
The last notable war of the nineteenth century has falsified the anticipations of nearly all the makers of small arms. The magazine rifle was held to be so perfect in its trajectory, and in the rapidity with which it could discharge its convenient store of cartridges in succession, that the bayonet charge had been put outside of the region of possibility in warfare. Those who reasoned thus were forgetting, to a large extent, that while small arms have been improving so also has artillery, and that a bayonet charge covered by a demoralising fire of field-pieces, mortars, and quick-firing artillery is a very different thing from one in which the assailants alone are the targets exposed to fire. Given that two opposing armies are possessed of weapons of about equal capacity for striking from a distance, they may do one another a great deal of harm without coming to close quarters at all. Yet victory will rest with the men who have sufficient bravery, skill and ingenuity to cross the fire-zone and tackle their enemies hand to hand.