To Hertz, however, belongs the honour of discovering how to generate these waves by means of sudden, sharply defined, electrical discharges. The principle may be illustrated by dropping a stone in smooth water. The sudden impact sets up a series of ripples all round the centre of disturbance, and the electrical impulse acts similarly in the ether. Indeed the fact that the waves flow in all directions from the central impulse is one of the difficulties of wireless telegraphy, because the message may be picked up in any direction by a receiver tuned to the same rate of vibration, and the interest for us consists in the hypothesis that thought-waves act in an analogous manner.

That vibrations are excited by sound is beautifully exemplified by the eidophone, an instrument invented, I believe, by Mrs. Watts-Hughes, and with which I have seen that lady experiment. Dry sand is scattered on a diaphragm on which the eidophone concentrates the vibrations from music played near it. The sand, as it were, dances in time to the music, and when the music stops is found to settle into definite forms, sometimes like a tree or a flower, or else some geometrical figure, but never a confused jumble. Perhaps in this we may find the origin of the legends regarding the creative power of Orpheus' lyre, and also the sacred dances of the ancients—who knows!

Perhaps some critical reader may object that sound travels by means of atmospheric and not etheric waves; but is he prepared to say that it cannot produce etheric waves also. The very recent discovery of transatlantic telephoning tends to show that etheric waves can be generated by sound, for on the 20th of October, 1915, words spoken in New York were immediately heard in Paris, and could therefore only have been transmitted through the ether, for sound travels through the atmosphere only at the rate of about 750 miles an hour, while the speed of impulses through ether can only be compared to that of light or 186,000 miles in a second. It is therefore a fair inference that etheric vibrations can be inaugurated by sound.

Perhaps the reader may feel inclined to say with the Irishman that all this is "as dry as ditch-water," but he will see before long that it has a good deal to do with ourselves. For the present what I want him to realize by a few examples is the mathematical accuracy of Law. The value of these examples lies in their illustration of the fact that the Law can always be trusted to lead us on to further knowledge. We see it working under known conditions, and relying on its unchangeableness, we can then logically infer what it will do under other hypothetical conditions, and in this way many important discoveries have been made. For instance it was in this way that Mendeléef, the Russian chemist, assumed the existence of three then unknown chemical elements, now called Scandium, Gallium and Germanium. There was a gap in the orderly sequence of the chemical elements, and relying on the old maxim—"Natura nihil facit per saltum"—Nature nowhere leaves a gap to jump over—he argued that if such elements did not exist they ought to, and so he calculated what these elements ought to be like, giving their atomic weight, chemical affinities, and the like; and when they were discovered many years later they were found to answer exactly to his description. He prophesied, not by guesswork, but by knowledge of the Law; and in much the same way radium was discovered by Professor and Madame Curie. In like manner Hertz was led to the discovery of the electro-magnetic waves. The celebrated mathematician Clerk-Maxwell had calculated all particulars of these waves twenty-five years before Hertz, on the basis of these calculations, worked out his discovery. Again, Neptune, the outermost known planet of our system was discovered by the astronomer Galle in consequence of calculations made by Leverrier. Certain variations in the movements of the planets were mathematically unaccountable except on the hypothesis that some more remote planet existed. Astronomers had faith in mathematics and the hypothetical planet was found to be a reality. Instances of this kind might be multiplied, but as the French say "à quoi bon?" I think these will be sufficient to convince the reader that the invariable sequence of Law is a factor to be relied upon, and that by studying its working under known conditions we may get at least some measure of light on conditions which are as yet unknown to us.

Let us now pass on to the human subject and consider a few examples of what is usually called the psychic side of our nature. Walt Whitman was quite right when he said that we are not all included between our hat and our boots; we shall find that our modes of consciousness and powers of action are not entirely restricted to our physical body. The importance of this line of enquiry lies in the fact that if we do possess extra-physical powers, these also form part of our personality and must be included in our estimate of our relation to our environment, and it is therefore worth our while to consider them.

Some very interesting experiments have been made by De Rochas, an eminent French scientist, which go to show that under certain magnetic conditions the sensation of physical touch can be experienced at some distance from the body. He found that under these conditions the person experimented on is insensible to the prick of a needle run into his skin, but if the prick is made about an inch-and-a-half away from the surface of the skin he feels it. Again at about three inches from this point he feels the prick of the needle, but is insensible to it in the space between these two points. Then there comes another interval in which no sensation is conveyed, but at about three inches still further away he again feels the sensation, and so on; so that he appears to be surrounded by successive zones of sensation, the first about an inch-and-a-half from the body, and the others at intervals of about three inches each. The number of these zones seems to vary in different cases, but in some there are as many as six or seven, thus giving a radius of sensation, extending to more than twenty inches beyond the body.

Now to explain this we must have recourse to what I have already said about waves. The heart and the lungs are the two centres of automatic rhythmic movement in the body, and each projects its own series of vibrations into the etheric envelope. Those projected by the lungs are estimated to be three times the length of those projected by the heart, while those projected by the heart are three times as rapid as those projected by the lungs. Consequently if the two sets of waves start together the crest of every third wave of the rapid series of short waves will coincide with the crest of one of the long waves of the slower series, while the intermediate short waves will coincide with the depression of one of the long waves. Now the effect of the crest of one wave overtaking that of another going in the same direction, is to raise the two together at that point into a single wave of greater amplitude or height than the original waves had by themselves; if the reader has the opportunity of studying the inflowing of waves on the seabeach he can verify this for himself. Consequently when the more rapid etheric waves overtake the slower ones they combine to form a larger wave, and it is at these points that the zones of sensation occur. If the reader will draw a diagram of two waved lines travelling along the same horizontal line and so proportioned that the crest of each of the large waves coincides with the crest of every third wave of the small ones, he will see what I mean: and if he then recollects that the fall in the larger waves neutralizes the rise in the smaller ones, and that because this double series starts from the interior of the body the surface of the body comes just at one of these neutralized points, he will see why sensation is neutralized there; and he will also see