this work is 55l. a year, the maximum 1007. The maximum salary of the second division of male clerks (lower grade) is 2501., whilst the higher grade of the second division of men are able to earn up to 3501. The disparity of salary holds good though men and women may be doing very similar, and in some cases identical, work.

Again, in the Pimlico Clothing Facory, 158. per week is considered a good wage for a skilled woman worker, whilst, in answer to a question in the House of Commons last session, it was ascertained that 238. per week is the lowest sum given to the most unskilled man laborer. It is an undoubted advantage to choose your employers by popular election, and it is easy to see how the men are able to bring pressure through the House of Commons to secure a fair rate of wages for themselves in the Government factories; whilst the whole weight and prestige of the Government as the largest employer of labor in the country goes to set an example of underpayment and sub-contracting amongst women. The effects of this evil extend far beyond the 30,000 women actually employed by Government, and react on the whole of the labor market. All local bodies are bound to keep down their expenses as much as they can. Government low rates have given them reason and justification for adjusting their wages to the Government standard; and directly one private emplorer, seeking naturally to buy labor at the cheapest rate, begins to follow the public example, other employers are at once bound by The Nineteenth Century and After.

The whole question of the relation of industry and politics is too involved to enter into here. But it is nevertheless true that, whether we like it or not, since the days of Lord Shaftesbury's Factory Act we have seen a great change, and a gradual shifting of the ground on which industrial questions are fought out. Technical difficulties relating to obscure processes in different trades are now national difficulties decided in Parliament. Working men have realized this, and the great sums of Trade Union money that in old days were kept exclusively for industrial objects, are now devoted unhesitatingly to parliamentary purposes. The employers also have their political organizations and methods of attack and defence. It is not to be wondered at if, in the clash of powerful conflicting interests, the grievances and claims of those millions of workers who are not allowed to make their voices heard should be ignored. The late Lord Salisbury said that the condition of the working women of England was a "blot and a menace to our civilization." Miss Stephen, on the other hand, congratulates women on possessing the key to men's reverence. It may be that she is right, that men reverence "sheltered" women; but this I do know, that there are many hundreds of thousands of half-starved wage-earning women who are seeking yet in vain the key to men's justice. Eva Gore-Booth.

Five years ago, in the month of February, in the year 1902, Mr. Marconi, travelling across the Atlantic in the steamship Philadelphia, received a

"wireless message" printed in ordinary Morse type from his station at Poldhu, near the Lizard. To-day such messages pass hourly between ships at sea, and

from ships at sea to stations on land, and "wireless telegraphy" has become a matter of such general importance that as I sit down to write this article representatives of the nations are assembled in Berlin to consider and, if possible, to regulate the various political and commercial interests involved in the new art. But in 1902 the thing was unique. How was it done? Who made it possible? And what is the physical basis of this newest invention built up with such mushroom-like rapidity by modern physicists? One thing seems clear. The man who "pressed the button" in 1902 was Mr. Marconi. But who set him to work? Who started the idea? And what equipment of data did the pathfinders provide for their successors? Was it Faraday, working, for the sake of quiet, first in a cellar at the Royal Institution, and later at the Shot Tower by Waterloo Bridge? Was it James Clerk Maxwell, the originator of the famous system of equations known as "Maxwell's Theory," or was it Hertz, with his "philosophical experiments" and their epochmaking results, who gave the impulse? Was it to one or all of these great pioneers that we owe the marvels of wireless telegraphy, and what was the nature of their contributions to the subject? Here we have problems enough to demand a whole number of the Cornhill Magazine for their solution. What can we do with them in a single article?

It will simplify our task a good deal if I say at once that, looking at the matter from the physical point of view and in the simplest way, there is no essential difference between the flickers of light used as signals by a savage tribesman when he waves a beacon to warn his friends a few miles away of the approach of danger, and the invisible signals sent over the ocean from the station at Poldhu. The savage with his torch and the highly trained electrician

at Poldhu each in his own way generates waves in that "ether" which, as we believe, permeates every speck of matter and fills every nook and cranny of the universe, and the success of the signal in the one case as in the other depends upon those waves falling upon a suitable receiver, the human eye or some substitute for the eye, at the end of their journey through space. And yet there is this difference between the light waves produced by the savage and the electric waves generated at Poldhu. The latter, to put it very broadly, for there is a big gap, may be said to begin where the former cease. For, while light waves are so small that many thousands of them can be packed within the compass of a single inch, electric waves are so big that they may be feet, miles, or even thousands of miles in length. In all essential qualities, however, except in size, light waves and electrical waves, so far as we know at present, are identical. The human eye is responsive to the small waves, but not to the big waves. That is why the big waves were not recognized until a special instrument had been constructed for the purpose.

The first electrician to construct an instrument which would detect electric waves, and the first to recognize an electric wave, was Heinrich Hertz. His account of his experiments was done into English a few years ago by Mr. D. E. Jones, and published under the title of "Electric Waves."

The questions asked on the first page of this article now resolve themselves into two which are comparatively straightforward.

How were electric waves discovered and identified with light waves? How have they been applied to "Hertzian wave telegraphy" by Hertz's successors? Before we can gain answers to these two questions, simple as they seem, it will be necessary to go over some old ground, and recall for a moment some of the fea

tures of the wave theory of light. If we do not do this, much that follows will seem unconvincing and vague, except to those who already are familiar with the undulatory theory.

Light, as we all know, travels through space in straight lines with a velocity in air of about 186,000 miles per second. When a ray of light passing through the air or any other gas impinges on a solid object, such as a sheet of polished silver or glass, it may rebound, or be "reflected"; or it may pass through the solid partly or wholly, according to circumstances, this being what occurs when the solid is transparent like glass or a diamond. In the latter case, as the ray enters the solid it is diverted from its original course, or "refracted," at the surface of the solid, and again diverted, but in the opposite sense, when it subsequently emerges from the denser and re-enters the rarer medium, the air. We all know, also, that ordinary white light is not homogeneous, but can be resolved into several components by means of a triangular glass prism, as Newton taught us in the seventeenth century. It is important to remember, further, that since Newton's time it has been discovered that all light is not visible to the human eye; that at our best we are but purblind creatures, and that besides the limited field of light corressponding to the colored band known as the visible spectrum there are other luminous radiations to which the human retina does not respond. This invisible light has been detected at both ends of the spectrum, some beyond the visible rays at the violet end of the spectrum, and some beyond the visible part at the red end. Thus to the physicist of the twentieth century the term "light" does not apply only to the light we see, but includes other rays which, though invisible to us, can be

1 Unless the ray falls perpendicularly upon the solid.

"reflected," "refracted," and polarized' like ordinary light. Radiations like the corpuscles of radium, which cannot be reflected, refracted, and polarized do not, in this sense constitute light, though they may generate light when they enter the eye.

If we could transport ourselves to the days of Newton, and listen to the discussions of the philosophers of the seventeenth and eighteenth centuries, we should find one of the burning questions to be this-Can matter act where it is not? Is action at a distance through a perfect void possible or impossible? To Newton the idea that gravity might be innate, inherent and essential to matter, so that one body might attract another at a distance through a vacuum without the mediation of anything else, was an absurdity into which no man having a competent faculty of thinking in philosophical matters could possibly fall. To the thinkers of the later part of the eighteenth century, when the influence of Boscovich predominated, on the other hand, the notion that gravity or electric or magnetic attraction might be propagated by a medium seemed as wild and ridiculous as the idea that matter could act where it is not appeared to Newton a hundred years before. To-day the wheel has turned again, and, guided by Thomas Young, Fresnel, Faraday, Clerk Maxwell, and latest of all by Hertz, we again seek the aid of an "ether" to account for the propagation of light, and to provide a medium through which and by which forces of attraction or repulsion seemingly acting at a distance are transmitted across space.

2 When a beam of light falls perpendicularly upon a plate of tourmaline cut parallel to the axis of the crystal, only part of the incident light passes through the tourmaline, and the properties of the transmitted rays lead us to suppose that in these all the vibrations are executed in one plane, and transversely to the direction of the beam. Such light is said to be "polarized."

If we abandon the emission theory of Newton, which teaches us that every self-luminous body emits minute material particles which cause the sensation of light when they fall upon the retina, and adopt in its place the modern view that light and radiant heat consist of waves, it seems to follow that these waves must be waves of something or waves in something. This something we call "the ether," and what we know about radiant light and heat assures us that this ether must not only fill all space and permeate every speck of matter, but must be very different from anything we are acquainted with at present. It cannot be solid like a stone, nor liquid like water, nor can it be a gas, for the most perfectly exhausted vessel can transmit light, and therefore must be full of ether; and while the ether must be far less dense than any known gas, and allow things to move freely through it, yet it must possess some quality closely akin to the rigidity of steel. What it is we do not know. We assume its existence and deduce its properties from what we know about radiant light and heat, and about the waves generated by the os cillating electric charges of the Leyden jar and similar electrical contrivances for producing flashes of artificial light ning. Without an ether, a wave theory of light would seem an absurdity. For if light consists of waves, and if the interstellar space be a mere void, what becomes of a ray of light emitted by the sun on its journey to the earth during the period of about eight minutes when it is neither on the sun nor on the earth? Is it not evident that the wave theory of light imperatively as serts the existence of an ether, and reopens the great question settled in one way by Newton, and in the opposite way by his successors in the eighteenth century? Up to to-day nothing has been done to settle this vexed question as applied to gravity. Indeed, Lord

Kelvin goes so far as to say that "up to the present time we have no light, even so much as to point a way for investigation in that direction"; but in the case of electric and magnetic phenomena the new physics has been more successful.

The wave theory of Young and Fresnel was scarcely established before Faraday observed that a strong magnet exercises a peculiar action on polarized light, and proposed, in 1846, as a subject of speculation, an "electromagnetic theory of light." This theory was developed twenty years later by Clerk Maxwell, who found the "elasticity" of the magnetic medium in air to be so nearly identical with that of the luminous ether as to leave little room for doubt that "these two co-existent, co extensive, and equally elastic media are really one medium, viz. the ether of the undulatory theory of light"; and before many years had elapsed it was held generally by the younger English physicists that electrical disturbances are transmitted by means of the ether, and that electric vibrations do not differ essentially from light waves. In 1883, at a meeting of the British Association, the late Professor G. F. Fitzgerald carried the matter a step further by proposing a method of producing electromagnetic disturbances of comparatively short wave-length by utilizing "the alternating current produced when an accumulator or storage battery is discharged through a small resistance," and that is how matters stood when Hertz turned his attention to the subject early in the year 1886.

Probably each of us has seen at some time the mimic lightning of a Leyden jar. If so, two things will be remembered. First, that at the moment of discharge there was a blinding flash between the two discharging spheres of the apparatus and that this was accompanied by a sharp crash or crack. Secondly, that both the flash and the