It is quite easy to photograph a sound, by means of a diaphragm beside which a soap bubble is thick, and to compare wireless sound with the original; even then we have the great difficulties of resonance, and a diaphragm cannot reproduce properly. How, therefore, dare we neglect the dreadful sounds we hear in the name of radio music? If a piece of silvering, one thirty-secondth of an inch, be scraped from the back of a mirror and fastened to the outer part of a celluloid diaphragm (made by water-floating a drop of amyl acetate in which celluloid has been dissolved), it only requires a horn and a beam of light to render visible the waves of sound. A diaphragm movement of a millionth of a millionth of an inch is sometimes audible. It is the science of wireless that is beautiful; it is the possibilities that are wonderful; but to talk of pure sound and to judge of it by the human ear which varies after every meal, is like measuring the amount of current passing through an electric-light bulb by feeling its heat with the hand. It is not generally known that, during the War, experiments were made with a sound-reflector for listening to different types of aeroplane and submarine, by means of a microphone placed at the centre of a concave mirror. The difficulty was that of distortion, which is the whole source of trouble with sound producers to-day. Distance is no difficulty and when we can obtain purity and realism as well as distance, the latter is no difficulty at all; then only will be the time when we shall have that spontaneous mental realism of vision that will help radio to alter the world. In a few years time we shall be able to chat to our friends in an aeroplane and in the streets with the help of a pocket wireless set, and be able to do practically everything by the aid of radio that we now do with our voice. The only thing that will seem intensely strange will be that these comforts never existed before! WIRELESS INACCURACIES I have often wondered whether people realise that broadcasting, at present, is only possible or, shall I say is only popular, because of its extreme impracticability for most forms of secret communication. Supposing two people had been able to converse privately and with absolute secrecy from other “listeners in,” then we should not mind trusting all our messages to Radio. At present, what can be coded can be decoded, and we are not entranced by the idea of entrusting our pennies to the winds of Heaven and the vagaries of a thunderstorm. If wireless had really been selective in the first instance, broadcasting would not have been its initial phase. Wireless at present is excessively inefficient; a few yards from a large broadcasting station the power is measured in millionths of a horse-power, is disseminated in all directions, and is almost without definite selectivity.