POPULAR SCIENCE MONTHLY.
telephone relay has been invented which preserves the form of the first utterance, the vowel a loses its delicate characteristics, and becomes simply a meaningless noise. It is maintained by some authorities that such a relay can not be invented, that it is impossible to preserve the delicate inflections of the human voice in passing from one circuit to another, even through an infinitesimal air gap or ether space. It is well, however, to reflect upon Hosea Bigelow's sapient advice "not to prophesy unless you know." It was maintained in the early days of the telephone that speech would lose so many characteristics in the process of transmission over wires and through magnetic apparatus that it would not be intelligible. It is certain that at present long-distance transmission of speech can only be accomplished by using more powerful transmitters, and by making the line of copper better fitted for the transmission—just as quick transportation from place to place has not been accomplished by quitting the earth and by flying through space, but by obtaining more powerful engines and by improving the roadbeds.
The hopes of obtaining a relay for wireless telegraphy seem as small as they do in telephony. The present method is practically limited to distances of fifty or sixty miles—distances not much exceeding those which can be reached by a search-light in fair weather. Indeed, there is a close parallelism between the search-light and the spark used in Marconi's experiments: both send out waves which differ only in length. The waves of the search-light are about one forty-thousandth of an inch long, while the magnetic waves of the spark, invisible to the eye, are three to four feet—more than a million times longer than the light waves. These very long waves have this advantage over the short light waves; they are able to penetrate fog, and even sand hills and masonry. One can send messages into a building from a point outside. A prisoner could communicate with the outer world, a beleaguered garrison could send for help, a disabled light-ship could summon assistance, and possibly one steamer could inform another in a fog of its course.
Wireless telegraphy is the nearest approach to telepathy that has been vouchsafed to our intelligence, and it serves to stimulate our imagination and to make us think that things greatly hoped for can be always reached, although not exactly in the way expected. The nerves of the whole world are, so to speak, being bound together, so that a touch in one country is transmitted instantly to a far-distant one. Why should we not in time speak through the earth to the antipodes? If the magnetic waves can pass through brick and stone walls and sand hills, why should we