IN the public mind, Signor Marconi and wireless telegraphy are pretty nearly one ; he is all of it. And for this there is some reason. Marconi was the first in the field, the first to send a wireless message several miles, the first to reach a hundred miles, and the first to cross the sea. He has had the lead, and he has it now. And this, in the face of a perfect host of competitors, is big achievement for a young man still under thirty. He deserves all the fame he has won. 
    Nevertheless, wireless telegraphy would probably be about where it is now, save perchance for crossing the Atlantic, if Marconi had never been, and it is not impossible he may yet be beaten at his own game. If he is, it will come about in this way : 
    The device which made wireless signalling possible was the very well-known coherer. This was not in the remotest sense Marconi's invention. He merely took it all ready made, and modified it in a way to make it much more sensitive. On this, and some other details, he secured rather broad patents. The alternative to other aspiring inventors was to go round the coherer, so to speak, or give up. 
    They went round, and in so doing discovered other devices so much more sensitive than the coherer that the latter was left in the shade. It has now been abandoned, for all long-distance work, and by Marconi himself. 
    What is true of the coherer is more or less true of all the various details of sending and receiving. For example, in the beginning the electric waves were produced with a Rubenkorff coil. This is essentially a laboratory instrument, and produces waves of enormous " frequency," that is, a million or two oscillations per second. Such high frequencies are not needed, and are ineffective. The induction coil has now been generally replaced by an ordinary alternating dynamo, coupled with a step-up transformer to raise the generating current to the required tension. These are everyday machines that can be bought anywhere. Signor Marconi has followed this procedure in his transatlantic work. 
    Again, the old Morse " inker," coupled with the coherer, and employed to register the wireless messages, was a very clumsy affair, and has now been replaced by an ordinary Bell telephone. So with many other technical points, such as using large " capacities "--electrical reservoirs, so to speak, to store large quantities of electricity where they could be suddenly loosed ; the employment of the closed " tuned " circuit, instead of the open circuit, as in the old way, and so on. 
    Now the especial point of the matter is that practically all these improvements of American invention, and are covered by American patents. And two big companies are in the field which will test Signor Marconi's right to employ the new methods. Forced to do new things, American inventors have found better ways : while Marconi with splendid courage, has been tackling the long-distance problem, and brilliantly bridging the Atlantic, they have gone ahead more quietly and worked out systems which seem more practicable from a commercial point of view. The first of the American systems to achieve a practical success was that originated by Dr Lee de Forest. He had taken his degree at Yale on a study of the Hertz waves, as the electric waves are generally called, and so came to wireless with a solid equipment. He employs the ordinary alternating dynamo and transformer, and seems to have been the first to do so. For the rest, his system is based on a receiver, or responder, as he calls it, working on exactly the opposition principle to the old coherer. It is a decoherer, and altogether an amazing affair. A very weak current is made to flow round a circuit and through the responder. When the Hertzian waves arrive they break this current. In a telephone introduced in the circuit, you hear a buzz, or rather a hum. The break is due to the formation of little air bubbles between the loose contacts of the responder. These air bubbles are instantly absorbed,--so rapidly in fact, that a succession of waves can be made to break the current a thousand or more times a minute. With the de Forest system it is possible to send as fast as in ordinary telegraphy--that is, fifty or sixty words a minute. The messages are taken by an operator listening in a telephone, just as if it were ordinary Morse telegraphy. 
    It is all so simple that it reads like a fairy tale. But it took a deal of patience and hard work to achieve ; and there were weary days when no one could be found to invest a dollar ; hospital days too, when the money did come, and an over-keen young man worked himself to a breakdown. 
    In recent competitive trials, the de Forest system appears to have won the government's favor, for both the War and Navy departments are equipping stations with its apparatus. It has been successfully employed between Washington and Annapolis--an overland test. Now it is making for the Pacific, and it may not be many months before we shall be in touch, by wireless, with our new possessions in the Philippines. 
    The second system of wholly American origin is that of Professor R. A. Fessenden, Professor of Electric Engineering in the Western University of Pennsylvania at Allegheny. These patents have only recently been taken out, although the first application dates from nearly four years ago. They cover a comprehensive plan, strikingly new in many details, and altogether the most up to date in the field. 
    Professor Fessenden's receiver is neither a coherer nor a decoherer. The electric waves are merely made to heat a marvellously thin wire, through which a very weak electric current constantly flows. The effect of this heating is to vary the current and operate a telephone. It is a good deal on the principle of Professor Langley's bolometer, the tiny machine which will register the heat of a candle a mile and a half away. The heating surface, however, is reduced to a bit of wire 1-5000 of an inch thick. It is invisibly small, and is enclosed in a vacuum and a metal shell. 
    Professor Fessenden calculates that this receiver is about 40,000 times as sensitive as the best types of the coherer. He has operated over fifty miles with a spark 1-32 of an inch across, where it required a flash 5½ inches long to actuate a coherer over the same distance. Probably with a device like this, Signor Marconi would have had no need for the tremendous outpour of energy which he used in signalling across the Atlantic.