Page:Popular Science Monthly Volume 64.djvu/167

Rh sometimes described as being extravagant in power, but, as a matter of fact, the most remarkable thing about it is the small amount of power really involved in conducting it. On the other hand, Hertzian wave manufacture is not altogether a matter of power. It is much more dependent upon the manner in which the ether is struck. Just as half an ounce of dynamite in exploding may make more noise than a ton of gunpowder, because it hits the air more suddenly, so the formation of an effective wave in the ether is better achieved by the right application of a small energy than by the wrong mode of application of a much larger amount. If we translate this fact into the language of electronic theory, it amounts simply to this. It is the electron alone which has a grip of the ether. To create an ether wave, we have to start or stop crowds of electrons very suddenly. If in motion, their motion implies energy, but it is not only their energy which is concerned in the wave-making, but the acceleration, positive or negative, i. e., the quickness with which they are started or stopped. It is possible we may discover in time a way of manufacturing long ether waves without the use of an electric spark, but at present we know only one way of doing this, viz., by the discharge of a condenser, and in the discharge of large condensers of very high potentials it is difficult to secure that extreme suddenness of starting the discharge which we can do in the case of smaller capacities and voltages.

How strange it is that the discharge of a Leyden jar studied so profoundly by Franklin, Henry, Faraday, Maxwell, Kelvin and Lodge should have become an electrical engineering appliance of great importance!

Whilst there are many matters connected with the commercial aspect of Hertzian wave telegraphy with which we are not here concerned, there is one on which a word may properly be said. The ability to communicate over long distances by Hertzian waves is now demonstrated beyond question, and even if all difficulties are not overcome at once, it has a field of very practical utility, and may even become of national importance. Under these circumstances, we may consider whether it is absolutely necessary to place the signaling stations so near the coast. The greater facility of transmission over sea has already been discussed and explained, but in time of war, the masts and towers which are essential at present in connection with transmitting stations could be wrecked by shot or shell from an enemy's battleship at a distance of five or six miles out at sea, and would certainly be done within territorial waters. Should not this question receive attention in choosing the location of important signaling stations? For if they can, without prejudice to their use, be placed inland by a distance sufficient to conceal them from sight, their value as a national asset in time of war might be greatly increased.