stones of the ruined castle at Airlie a little house to which he retired. Speaking with a slight French accent, with a French cook and butler, and always wearing the dress of a Colonel of the French Guards, he passed the remainder of his days riding about his lands, helping, out of the pittance left him, the descendants of the men he had led so many years before on a fruitless quest. Even this was diminished, as, after the execution of the King of France, he refused to receive his pension as a French officer from Napoleon, who proposed to continue it and to pay the arrears. He would never consent to

ask the removal of the attainder. The present writer has spoken to one who knew him well, as a tall, handsome, dignified old man, who slipped quietly out of life on March 3, 1803.

The romance ends for the moment, though the book continues with the lives of the later Earls, and tells how the attainder was removed just before the birth of the eighth Lord Airlie, but, except to the historian, these details are not of great interest. The life of the ninth Lord Airlie whose story completes it, vividly recalls that of the first Lord in valour, in piety, and in character, and after his death in action at Diamond Hill, the words of Lord Roberts, I deplore the death of that gallant soldier the Earl of Airlie,' fitly conclude such a family history. There may be a few slight inaccuracies, but these are generally matters on which different opinions are held by Scottish historians. This book, coming as it does at a time when the old system of land ownership in Scotland is fast disappearing, is of remarkable interest. It shows both the good and the evil of the past, and gives rise to the thought that most systems are fitted to their own times, and that change is not necessarily a condemnation of what has existed before. It also shows the value of those cardinal virtues of courage, faith, mercy, and love, which are perhaps too lightly regarded in the present remaking of the world.

Art. 11.-BROADCASTING.

THE influence of the service of broadcasting on the lives and affairs of men and nations, is already recognised as great in esse, and illimitable in posse. For a better com prehension of the subject it is advisable to refer briefly to the nature of the scientific operations which render it possible for an innumerable company to attend on that which may interest or concern them, irrespective of the distance which separates them from the event and from each other, and of the absence of any tangible means of communication between them and its passage. It is pertinent, also, to explain in a few words what the British Broadcasting Company is, how it came into being, and to indicate something of the policy and the ideals which inspire those to whom there have been committed such onerous and manifold responsibilities.

No matter in how technical or exhaustive a manner one might essay to explain the means by which wireless communication, telegraphic and telephonic, is made possible, one would sooner or later pass from the light of definite knowledge through the haze of the borderland of scientific investigation, into the mysteries and infinities of ignorance. For 'wireless' is manifestly dependent for its functioning upon the universal ether, a fascinating but illusive, and probably incomprehensible, medium. This mysterious ether, all-pervading, self-contradictory, by which all things consist and are upheld, impossible but mathematically proved, one of the final entities of the universe, is a mental conception fantastic or appalling to us. In daily life we live by assumptions. We assume knowledge to cover our ignorance. If the assumption works we are content. So in the preliminary stage of converting speech or music or other sounds into the form in which they may be conveyed across vast reaches of space, and in the final stage when the etheric disturbances are transferred back again into the realm of vibrations, which make them once again recognisable to our sense-perceptions in their original shape, it is convenient to speak as if we understood the nature of electricity, so familiar are we with its application, over looking the disaster of the schoolboy who had 'for gotten' what electricity was—which the Almighty and

ie alone had known. Even with the incomprehensible amiliarity works its way. When we switch on the light he electricity 'runs along the wire,' and there are so nany convenient and plausible explanations at hand that we may disregard the little protests which indicate that it is not all so simple as it appears. With wireless there is that solemn and inexplicable gulf between the two aerial wires a hundred or a thousand miles apart.

It is not altogether simple to explain the action of a wireless transmitter and receiver in such a way as to be scientifically accurate, and yet intelligible to the nontechnical mind; it may be helpful to resort to analogies which introduce well-known facts and occurrences similar to the phenomena which take place in wireless. It is so amazing to an unscientific mind that sounds, or rather their electrical equivalents, are able to traverse vast spaces of sea and land without some apparent medium to carry them. By the ordinary telephone, communication between two points is set up with the aid of wires running between them, and we think of the current of electricity flowing along the wires, and realise that this current would immediately cease were the wire connexion to be broken. In wireless, as I have said, the medium for the conveyance of the message is not apparent. It might first be thought that the electricity was carried by the air, but this is proved to be wrong by the fact that it passes through a vacuum or a brick wall with equal facility and disregard. We must, therefore, fall back on our imagination and concentrate on the idea of a medium which pervades everything. What the ether really is no one can tell us, but it forms a convenient basis for our theories; and having assumed that such a thing exists, we can construct reasonable explanations of the phenomena of electricity which are apparent to us, and which do us good service.

How, then, can we make use of the ether in order to establish communication between two points, without the aid of a visible connecting link? If a stone be dropped into the middle of a quiescent pond, the water is disturbed and waves are formed which gradually spread outwards in circles of increasing diameter. The surface of the water, radially from the centre of the disturbance, is a series of crests and depressions, and

the difference in level between succeeding crests and depressions gradually decreases; in other words, the waves reduce in amplitude until they are negligible and invisible. The horizontal distance between any two succeeding crests is, however, constant, and is dependent upon the size and weight of the stone, the height from which it was dropped, the depth of the water, and other factors. If we could arrange to drop several stones into the water, one after the other, we could maintain these waves indefinitely, and we should have created a means whereby the surface of the water could be kept in a constant state of up-and-down motion. Now, imagine that the stone be replaced by a transmitting aerial, and the water by the ether. We gave energy to the stone by dropping it, and we can give energy to the aerial by means of an electrical arrangement which involves the use of what is the most wonderful and most useful invention connected with wireless, the thermionic valve. The aerial in its turn gives out its energy, and in so doing disturbs the equilibrium of the ether, creating waves in it similar in shape to those formed on the surface of the water. There is one important point in which the analogy fails, which is that, in the case of the water, waves were formed in a horizontal direction only, whereas in the ether waves are sent out in all directions. These waves are electro-magnetic, and gradually die away as the distance from the transmitting aerial increases. The distance between any two consecutive crests is constant as it was in the analogy, and this distance is called the 'wave-length' of the waves which are being radiated and the station which is transmitting. By suitable means we can continue the supply of energy to the aerial, and thus keep the radiated waves constant in amplitude or depth as well as in length.

It has been found that electric waves travel at the same speed, 186,000 miles per second. This speed is tremendous, and, to all intents and purposes, their passage is instantaneous. We can easily calculate and control the wave-length, and, therefore, by simple division we can find out the number of times per second that the waves alternate up and down. This figure is called the frequency of the radiated wave and, for the wave-lengths used for broadcasting, its value is about

Fone million. In mathematical terms, the shape of the waves is said to be sinusoidal, and they are said to oscillate, that is, to alternate up and down, at radio or high frequency. We have, therefore, succeeded in producing a radiation of constant electro-magnetic waves from our transmitting aerial into the ether, and these constitute what is known in wireless telephony work as the 'carrier wave.' This is inaudible, though occasionally it communicates a slight hum due to the generators.

The problem next to be faced is how to vary or modify this carrier wave so that it will be able to represent in some way the sounds which are about to be produced in the broadcasting studio. Let us trace what happens. In the studio is a delicate piece of apparatus called the microphone, whose function it is to convert the sounds into their electrical equivalents. Sounds consist of air impulses, and in one well-known type of microphone these impulses are made to act on a light coil of wire suspended between the poles of an electromagnet. Now, when a coil of wire is moved in a magnetic field such as this, an electric current is set up in the coil, the strength being proportional to the rate at which the coil is moved, and in this case it is obviously related to the strength of the air-impulses which come from the voice or the orchestra. Loud sounds produce relatively big impulses in the air, which in turn move the coil, and, therefore, we have a device which will convert the sounds into their equivalent electrical energy without distortion. An exactly similar operation takes place when speaking into an ordinary telephone; but in this case slight distortion generally takes place which affects the quality at the other end of the line. In broadcasting, however, no distortion of sound can be allowed, and much research has been carried out to obtain perfection. Having achieved the conversion, the electric current so produced is said to vary at audio frequency, this frequency being very much smaller than the radio frequency which was referred to in connexion with the carrier wave. This varying current is led along wires and passed through apparatus known as a thermionic valve amplifier. This multiplies the current many thousands of times so that we are able to handle it with greater ease. It should be noted that the current