THE SECRETS OF THE ETHER.*
Moe. OWEN, who is Lecturer on Physics at the Birkbeck College, has done a useful piece of work in reprinting a series of articles which he contributed to the Electrician during the past two years. These articles deal with various advances lately made "in some of the recently acquired provinces of Physics," such as are barely, if at all, mentioned in available text-books. They mostly involve those fascinating researches into the ultimate secrete of matter which have taught us to see in the chemical atom a whirl of clashing electrons, and have brought us back to the ancient philosophical conception of a single Ur.stof or prima materiel; of which the whole uni- verse is composed. Perhaps the most remarkable chaplet., to the general reader, is that in which Mr. Owen gives an account of recent inquiries into radiation. We are constantly hearing of wonderful new kinds of rays, called generally by letters of the alphabet, which are to reveal thought, to end war, and to do all sorts of amazing things. It is interesting to learn from Mr. Owen what is actually known about waves in the ether. Ever since eyes were developed, in the wonderful upward course of evolution, one set of ether waves has impressed itself on living organisms. Light is caused by this set of waves, • Recent Physical Research. By David Owen. London: The Elecfriohne" Publishing Co. [3..13d. set.] . which vary in length from about one thirty-thousandth to one sixty-thousandth part of an inch. The visible solar spectrum exhibits the whole series of light waves, the shortest being at the violet and the longest at the red end. In 1800Herschel proved the existence of invisible heating rays—the infra-red rays— lying outside the visible spectrum. The invention of photo. graphy further showed that there were other rays, the ultra- violet, too short to affect our eyes, but capable of impressing themselves on a photographic plate. In 1887 Hertz dis- covered the electric waves, now used, in wireless telegraphy, which are ether wavee just like those of light, except that they are very much longer. He thus gave the experimental verifi- cation of Clerk Maxwell's theory that light waves are a particular form of eleetro-magnetic pulses in the ether. During the last few years a wonderful advance has been made in mapping out the spectrum of ether waves, and we now believe that the ether propagates waves of all lengths, from the infinitely small to the infinitely great ; we have actually traced the physical effects of the greater part of these waves. The shortest waves yet known are those of the X rays, which are so tiny that at least two hundred and fifty millions of them go to the inch. This corresponds very closely to the diameter of the average atom us established by Sir J. J. Thomson and his fellow-workers in the infinitely little, but the electron is yet a hundred thousand times smaller ! Above the X rays there is a gap of still unknown radiations, till we reach the smallest ultra-violet rays yet known; these run about two hundred and fifty thousand to the inch. Then we come to the visible light rays, ranging from sixty to thirty thousand to the inch. Thence the infra-red rays have been traced by. Ruben—whose latest work is singled out for special description—up to a length of one seventy-fifth of an inch. Then comes another gap of unknown rays, and then we reach the electric rays, which have now been traced from a minimum length of one-sixth of an inch up to practical infinity. It is marvellous to read of the patient investigations which have resulted in so vast an extension of natural know- ledge, and which are bringing about a revolution in physics of which the last generation could not even dream.
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