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means, we have learnt that electricity is the most universal of agents, and now we are learning, also by indirect means, of the existence in nature of hitherto unsuspected subtle emanations, electrically charged radiations, and radiations to which no substance is opaque.
The most plausible hypothesis respecting the radiations of the X-rays type is probably that which was formulated by Stokes-namely, that they are ethereal vibrations which differ from light as noise differs from music; that is to say, that they do not belong to that series of rays produced by continuous rhythmic vibrations, which includes light, radiant heat, and the electro-magnetic waves which are utilised in wireless telegraphy, but that they are irregular pulses in the ether. In the case of the Röntgen rays, the pulses would be produced by the impact of the cathode rays upon the surfaces which check them ; in the case of the y-rays, by the ethereal commotion caused by the emission of the charged radiations. In 1902, Blondlot noticed that if Röntgen rays fell upon a small electric spark they somewhat increased the brightness of that spark, and he thought to utilise this effect in an elaborately devised experiment for obtaining the velocity of the Röntgen rays. The velocity he found by this means was equal to that of light, and this seemed an important step towards knowledge of their nature. As he proceeded in his experimental work, however, he noticed that the rays which affect the spark were polarised, and that these polarised rays could be refracted by passing them through crystals. But it is abundantly evident that X-rays cannot be refracted, and therefore Blondlot perceived that there must be some mistake in the conclusions at which he had arrived. A simple test experiment made the matter perfectly clear. He interposed a prism of aluminium between the source of the X-rays and the spark, by the appearance of which he had thought to detect their influence, choosing aluminium because it is a substance which is transparent to X-rays and opaque to visible light. The X-rays passed undeviated through the prism, and produced no effect whatever on the spark. When, however, the spark was shifted into a position in which it was struck by rays which were deviated by the prism, then the former effect was perceived. Thus Blondlot saw that he had not succeeded in measuring the velocity of the Röntgen rays, but that he had discovered, mixed with them, some extremely penetrating rays which had the physical properties of ordinary light.
Further study has made him feel certain that these N-rays, as he calls them, do belong to the same category as light. They produce none of those photographic or phosphorescent effects which have so greatly aided the study of the Becquerel rays, and the only characteristic by which they can be recognised is that they cause a change in the luminosity of pre-existent phosphorescence, or of any feeble light or feebly illuminated surface-a change which it requires some practice to be able to appreciate, and which is not visible to every observer even then. On this account Blondlot's conclusions are not
yet universally accepted. One objective proof of the correctness of his observations has, however, been furnished. If a small electric spark is caused to produce a photograph of itself—all necessary precautions being taken to avoid error—the difference that it makes in the photographic appearance of the spark, whether it is being acted upon by N-rays or not, is marked and unmistakable.
Blondlot has measured the wave-length of the N-rays by methods similar to those employed for ordinary light. As a source of the rays he uses a Nernst lamp, enclosed in a dark lantern, with a window of aluminium, thus effectually cutting off all luminous rays. In front of the window there is a screen, formed of layers of aluminium and black paper, to cut off all the heat rays which proceed from the metal. This precaution is especially necessary in all these experiments, seeing that phosphorescence is so extremely sensitive to heat. Since N-rays do not pass through water, if it is pure—though they do pass through salt water, as well as through aluminium, wood, and many other substances-a screen of wet cardboard in which there is a narrow slit permits of the isolation of a beam, which can be focussed and dispersed by lenses and prisms of aluminium. Like the visible rays, the N-rays are heterogeneous ; the wave-lengths that have been measured vary, but they are all at least a hundred times smaller than that of the furthest ultra-violet rays that had been hitherto known--rays which do not reach us from the sun at all, since they are entirely absorbed by the atmosphere, and which, when obtained from the electric light, must be measured in vacuo, for a very little air is as opaque to them as if the air were lead. Yet the N-rays, which lie so very much further beyond the violet end of the spectrum, are largely contained in sunlight, thus proving that they lie outside the limit of the radiations which the air cuts off. N-rays are absorbed by many substances, and then afterwards emitted ; whether changed or not in character we cannot yet tell, but in any case there is here a close and important analogy with phosphorescence.
The point, however, which is perhaps of the most general interest with respect to these researches is this. There seems to be clear evidence already that there are other radiations besides those the wave-length of which has been determined, which are being discovered by means of this new test. Some of these may belong to a totally different part of the long series of ethereal vibrations which reach us from the sun, while others may be of an entirely different order. For the present all the radiations, which had not hitherto been detected, and which produce the same effects as the rays which Blondlot noticed at first, are grouped together as N-rays; but there are physicists who believe that further study will enable important distinctions to be made, and that with respect to this whole subject of invisible radiation, in the widest acceptation of that term, we are only on the threshold of discovery.
We cannot change our climate. Is it not possible to greatly ameliorate the part it plays in two propositions of grave national importance ? These are
(1) That the climate of these islands is in the main favourable to the development of certain diseases widely prevalent within its range, and adding great numbers to our yearly death-roll.
(2) That the atmospheric conditions of the life of the poor in London and other great cities are not, and probably never will be, favourable to the healthy development of the race.
As air is the first of our vital needs, so what may be called 'atmospheric hygiene ' is the first force by which both these dangers should be met. It has been the last to attract the attention of the public or to engage the resources of science. It is true that public faith, so long fastened on the medicine bottle, has been in some measure diverted to Open Air as a curative formula ; and that sanitary science, not confined to drains, to food, and to water, has included in its purview questions of ventilation and cubic air space per individual. It is with the first subject, which in many of its aspects includes the second, that this article is mainly concerned.
The gospel of Open Air has been widely preached, and has made many converts ; large funds have been generously provided for putting the doctrine into practice, and an ample measure of success has already been achieved. Do not these facts justify the hope that when the real nature of the question at issue is understood, and its vast potentialities are revealed by closer examination, neither science nor philanthropy will be satisfied to stop at the threshold of progress ?
Quantity has been the chief guide hitherto in the application of air, whether to disease or to overcrowded habitations. But the quality of the air, its condition, its properties, its intricate composition; the bearing of these on the special requirements of different complaints ; the suggested possibility of assimilating the air of our climate to that of other climates known to be beneficial to particular diseases, so converting it into a curative agent before it is breathed by the patient Vol. LVI-No. 329
these offer a vast field of investigation, and perhaps a rich harvest of relief to a multitude of sufferers. Few and shallow as yet are the furrows which science and medicine, working hand in hand, have driven in that great field. In another country a munificent endowment has been given by a patriotic citizen for a systematic investigation of the nature and treatment of consumption. But consumption is only one of the diseases which come within the scope of treated air. Already, happily, the first experiment in this greater subject has been tried, the first results achieved and demonstrated, in Englandin London. If we stand still, and the organised investigations of American science and medicine should in the end point to this as the true line of progress, what will then remain to be said of us here in England ? That, shutting our eyes to the light, we were content to lag behind, to follow only where others led the way, and to leave the credit of a great achievement to a more enterprising and more generous nation.
The necessity of the case arises from two causes, the one natural, the other artificial but permanent; for the conditions of our population as to residence are not less fixed than those of our climate.
Our climate is not all bad. It is a question whether on the whole any other could have been of greater advantage. We are still surprised at times at its behaviour, as though not yet perfectly familiar with it. But as a fact we are acclimatised, not perhaps in the sense of our trees and vegetation, or of some extinct race of aborigines for whom the climate was made and who were made for the climate. We are not grown
in it as a race; but after some centuries of habitation we have grown to it. The asperities of the British climate did not drive our imperial conquerors from their cherished Ultima Thule ; and successive races of invaders have held it dear. Indeed, they have thriven and prospered, enduring climatic hardship to a good purpose, it would seem.
Some enthusiasts hold that it is the best of climates. It hạs promoted open-air life and sport; and it was in England that the Open Air treatment was first preached by Bodington, and in Ireland by MacCormac, long before the crusade against consumption, Undeniably it has kept us a strong race. Physical deterioration,' which is under investigation by a Royal Commission, is really due not to the operation of climatic influences, but to their partial suspension by artificial conditions of life. Nor is our climate devoid of moral effect in the formation of the national quality of patience. Temperate,' in a technical sense, its merciless variability is a mental as well as physical discipline. It is a universal exerciser ' not only for the body but the mind, preparing us to sur
· The Henry Phipps Institute, at Philadelphia ; an admirable instance of the endowment of a fully-equipped institute for the progressive study of the prevention and cure of a single disease, until that disease shall be rendered preventable and curable.
mount obstacles and endure disappointments which we cannot foresee, and stimulating us like the rigid alternations of the hot and cold water douche.
It is not, however, with the virtues but the shortcomings of our climate that we are now concerned. Good as it is for health, it is also good for the prevalence and development of some of our diseases-so good, in fact, that we may classify them for the present purpose as climatic diseases. We have got rid of ague ; not, it is significant to note, by treating the complaint, but by treating its cause. Land drainage would banish ague even from the swamps of Africa. But consumption, with its insidious approach, its long delay, its fatal end; rheumatism, reading heart disease for so many; kidney disease, in its chronic form; bronchial diseases, lightly termed ' affections'; gout, with its evil connections for all these the best cure is climate of another kind.
Thousands of fortunate people pursue that cure, on the Riviera, at Davos, in Colorado, Mexico, and many other places too numerous to mention, where special virtues have been found in the climate. Yet there remain hundreds of thousands, the vast majority of the sufferers, whose means do not and never will enable them to leave this country, who are thrown back ceaselessly on its climatic disadvantages, and compelled to carry on a long and often hopeless struggle with a natural and native foe. Their helplessness appeals to us, and should not appeal in vain if, as we believe, a great measure of emancipation is consistent with economic conditions that cannot be altered.
It is the story of Mahomet and the mountain. If the patient cannot visit other climates, the air of other climates should be brought to the patient. The elemental forces in the air of those climates which make for cure exist in part in ours, but Nature has made them subordinate to other and less favourable forces ; science may suppress these and bring forward those. If they do not exist, science may some day produce them. Then to some extent in any building, however large, more completely in an enclosed cubic space, the patient would be enabled to breathe air which by scientific treatment had been assimilated in its essential properties to the air of health resorts thousands of miles distant from England.
This proposition, startling as it may sound, is already passing out of the stage of theory. At an institution ? known for its successful treatment of wounds, ulcers, and lupus by oxygen and ozone, a significant example has been given by the erection of enclosed cubicles, in which consumptive patients breathe treated air, and are subjected to conditions analogous to those which cure consumption at places like Davos or Tenerife. We learn that encouraging
• The Oxygen Hospital, Fitzroy Square, under the patronage of H.R.H. Princess Louise, Duchess of Argyll.