not upon the material of the substances through which they pass. When the Röntgen rays strike a surface they in their turn give rise to secondary rays of more than one kind, some of which, when the surface is a metal, are "cathode" rays, such as those drawn out of a metal by ultra-violet light.

The cathode rays may be said to be the foundation stone of the new branch of physics called radio-activity, so that the investigations begun by Hittorf and Crookes a quarter of a century ago into the phenomena connected with the passage of currents through rarefied gases, and which were then considered by many to be a sort of scientific trifling, are leading to vast results. When any substance produces fluorescence, blackens the photographic plate and ionizes the air, as the cathode and Röntgen rays do, it is said to possess the property of radio-activity. The discovery of radio-active substances followed on that of the Röntgen rays, which gave a great impetus to research. In the laboratories all over the world experiments were undertaken in order to find rays with the same wonderful penetrating powers, which should be independent of an electric current. It was thought that the rays were connected in some way with the substances that fluoresce, and Becquerel made experiments with fluorescent salts of uranium, to find out whether they also had the power of blackening a photographic plate through an opaque wrapper. exposed them for several days to sunlight, then brought them into a dark room, and found that this was indeed the case. He thought that the absorbed energy of the sunlight not only produced the fluorescence, which was a familiar phenomenon, but also these penetrating Röntgen-like rays. But one day, when for some reason the exposure to sunlight had been omitted, it was found to make no difference at all. The rays proceeding from the uranium

He

salts were not dependent upon a previous supply of energy from the sun, nor did time bring any diminution of their power. In 1898 G. C. Schmidt was able to show that compounds of thorium send out similar rays. The minerals, which contain, among many other elements, uranium and thorium, may be called natural radio-active substances. From these natural radioactive substances far more powerful radio-active substances have been extracted by chemical means, and new elements have been discovered, the best known being radium, pure salts of which were first obtained by Professor and Madame Curie from the mineral pitchblende, a uranium ore found in Bohemia.

In the present state of our knowledge, when almost every week brings new facts to light, no generalization on the subject of radio-activity is possible. Suffice it here to quote the words of the Times of the 26th of June of last year: "Matter in quantities invisible under the microscope, unweighable on the finest balance, and beyond the range of detection even of the spectroscope, can be accurately studied and quantitatively investigated if it possesses the property of radio-activity."

Scientists are not agreed as to the source of energy of the Becquerel rays, rays capable of doing "work" in the scientific sense of that term, without any energy being supplied from without, to our knowledge. Lodge, Crookes, Rutherford, and many others are advocates of the disintegration theory, namely, that the elements in question are disintegrating at an extremely slow rate into other elements, so that the source of energy is the internal energy of the chemical atom. Madame Curie and others think that the energy of the radio-active substances does come to them from without, that they are able to absorb the energy of rays of some sort which pass through other

substances unperceived. But on this point all are at one: that the discovery of the radio-active elements is revealing facts hitherto absolutely undreamt of; that, as Professor Grätz says, there apparently is, behind the world of phenomena as we know it, an entirely unknown region the very first coast-lines of which we are only just beginning to perceive.

Such an extension of our knowledge naturally brings with it a shaking of the foundations, and at least one eminent chemist has called attention to the fact that, after all, our chemistry is only the chemistry of the means at our disposal; that our very greatest heat, the heat of an electric arc, which breaks up all molecules into atoms, is insignificant compared with cosmical heat, and that we have no idea what the effect of other conditions might be. It has been thought for some time that chemical affinity is really electric in essence, but it has not yet been possible to work out any satisfactory theory. On the electric theory of matter, namely, that atoms are complex-"an aggregate of smaller bodies restrained and coerced into orbits by electrical forces"-chemical affinity should admit of an electric explanation. Experi

ments with radio-active substances seem about to confirm the electric theory of matter in an astounding way. Of the three principal kinds of rays given off by a radium salt-distinguished by some scientists as a, ẞ and y-the a rays are the most easily absorbed. A metal plate will shut them off, and enable the more penetrating rays to be studied alone. These rays will produce a dot of light on a phosphorescent screen. If now electrical and magnetic forces act on the rays, then there appear on the screen а fainter, undeflected dot and a band of light; the band and dot being separated by a space. The fainter dot is caused by the undeflected γ rays and the band

of light by B rays of varying velocity. These Brays are found to be streams of electrons, like the cathode rays, but with a velocity approaching one-third that of light. And the result of mathematical calculations based on the experiments was, that at velocities so high as this, the mass of the electron was no longer a constant. Now mass, if it really is mass, cannot become a function of the velocity, so it was evident that part at least of the mass was apparent and due to the inertia of electricity known under the name of self-induction. Indeed many physicists consider it proved that not only a part, but the whole, of the mass of the electron is apparent, from which it follows that "cathode rays," whencesoever obtained, consist of pure negative electricity.

And there are men who are now going a step further still. They say: "If forces that are purely electro-magnetic produce exactly the same effects as would be produced by the inertia of matter, perhaps all matter is in the same sense only apparent." At present the phenomena of physics are, as it were, divided into two camps: acoustics and heat, which are explained from the laws of mechanics; and electricity, with its subdivision light, which has not been satisfactorily thus explained. For half a century we have tried to explain electricity mechanically, and may be said to have failed; let us now try to explain mechanics electrically, and see where that will lead us.

Perhaps it is a mere matter of words whether we say that all matter is electrically charged or that all matter is modified electricity. But it may lead to the most far-reaching conclusions if, in explaining phenomena, the laws of electricity should be taken as the premiss from which we start, instead of, as hitherto, the inertia of matter. And, inasmuch as the more nearly any explanation approaches the truth, the better does it point the way to fresh

knowledge, the fact that so radical a change may be about to take place is one of the reasons why there is a feeling of expectancy in the air. It is hoped that light may be thrown upon The Nineteenth Century and After.

universal gravitation and other obscure problems, and it is suspected that science is trembling on the verge of something great.

Antonia Zimmern.

It is the charm of association, rather than actual beauty, that attaches us to a city or a scene. Quebec, Chungking, and Edinburgh are alike beautifully situated, and were it not for the associations that cluster round Holyrood and the Castle and the Tolbooth, Princes Street might still be as fine a promenade, yet how infinitely less interesting! Thus though Chentu, the capital of China's westernmost and largest province, is not endowed with the beauties of "mountain and water" (mountain and water-landscape in Chinese) of the commercial centre, Chungking, yet its historical memories give it at once a sentimental value, only accentuated by its stately groves, its great flights of birds, the tense attitude of its officialdom since the advent of the present Viceroy, its population of artisan shopkeepers working late and early, together with its centuries-old, all-enchaining Chinese customs, each to us stranger than the other. Amongst all the many cities of China that I have visited, this is the first of which I could understand even a foreigner saying that he would by choice live there.

Situated on the well-irrigated plain that owes its riches to Li Ping, who some 200 years B.C. conceived the idea of cutting a way through a hill for the river of Ouanhsien, thus adapting the plateau for rice-growing, unknown there during the previous Chin Dynasty, Chentu is the centre of a rich agricultural population yearly reaping three

crops of a greatly varied nature. Its walls can only be compared with those of Peking; 27 feet high, 37 feet broad, so that twenty-five men can walk abreast on the top, they are unlike those at Peking in that they are not overgrown with grass and bushes and decayed by time, but kept in capital condition. Only interspersed with occasional guard-houses, they present an unbroken promenade save for the one interruption of the Manchu city sheltering crescent-wise under the wall beneath the west and north gates. There are but four gates or outlets to the world for all this crowded city full of three hundred thousand persons, and the consequent over-pressure at the east gate, by which all direct communication is carried on with the great trading emporium of Chungking, and all boat communication via the Min river with the Yangtse, that great thoroughfare of China, is a thing to be seen rather than imagined. Never save in Peking in the old days was there surely anything like it.

The city, or rather settlement, where the Manchus live, is shut off by walls and gates from the rest of the city. It is a region of lofty trees, peopled at night by many birds, with a parade ground where the Manchu men do that one bit of service to the nation in return for which they and their families live as pensioners upon the Chinese nation, generation after generation. There Manchu women stand before their

doors, each with a flower far projecting on one side of her head, be her age what it may, and in a long gown falling ungirt from the shoulders to the feet in straight lines, save when in winter a brazier is tied on underneath for warmth. Slatternly but highly rouged, the Manchu ladies can both walk and stand on their high-heeled clog-like shoes as well as their Chinese sisters of crippled feet-three inches seems to be not the minimum but the average foot-length in Chentu. Yet day after day and all day long they seem to find nothing better to do than to hang about outside their elegant entrance gates and gaze down the quiet roads, which are like English lanes with their overshadowing trees. There is a reserved, farouche air about them, and if addressed they quickly take refuge in the little gardens which they are said to keep tidy. But a more dispiritedlooking set of hangers-on it would be difficult to discover than these Manchu pensioners, none of whom have been permitted for centuries to add to their pensions by trade or industry.

There is again another walled-off city in Chentu. Like the Forbidden City, or palace enclosure in Peking, there is here the Yellow City, sometimes called Liu Pei's city, where stood the palace of this remarkable man, who from being a poor lad selling straw sandals in the neighborhood of Peking pushed right across China and established one of the celebrated Three Kingdoms in Szechuan, somewhere in the third century A.D. It is true he claimed to be a lineal descendant of the Han Emperors. Now row beyond row of cells occupies the ground for the use of candidates at the great examinations, at which, for example, in 1897 13,000 students went up, and there were but 96 places to be distributed. Thinking over these figures one begins to understand the gilded characters over some of the more stately resi

dences in Chentu, signifying that a man who has won his degree lives within. It is a relief to turn to the quiet streets off which stand these retired residences and to quit the intensely busy shopping streets, crowded from morning to night with an ever jostling crowd of carrying coolies each with two baskets dangling from either end of his pole; of horribly creaking wheelbarrows, on which sometimes bound-foot women are pushed along, not sitting on either side of it as in an Irish jaunting car after the fashion of the east of China, but flouting the street in the attitude a lady assumes on a lounging chair in her own drawing-room. Here are Mandarins looking through the glass windows of their sedans, pale-faced and grave-visaged but be-necklaced and befeathered for all the big goggles through which they stare somewhat blankly, gaily liveried pursuivants clearing the way before and attendants on horseback bringing up the little procession; beggars clacking bits of wood to attract attention, their legs and arms showing sharp pointed beneath the one mat the poor creatures clutch round themselves, sometimes with the air of being proud of having even that.

The great centre of Chentu is, however, not the Yellow City, which in material fact holds that position, but the Viceregal Yamen and official residence, where, beside the arsenal and between the south and east gates, at this present reigns Tsên Chun-hsüan, aged only forty-three, but already one of the most dreaded Viceroys in China. He came here with the reputation that he would as soon cut off a man's head as look at him, and he has well kept up this character during the few months since his arrival. Heads have fallen in plenty, the province is terrorized, foreigners now wander through it unafraid, policemen innumerable with wands and uniforms keep order in the streets of Chentu. But no rain falls;

in the belt of mountain land stretching east and west to the south of the city the people starve, and the Chinese vor populi says Heaven is displeased at so much bloodshed. This Viceroy is reckoned one of the most enlightened officials of China; he has contributed towards the Society for the Diffusion of Christian and General Knowledge in China, he is putting out a proclamation against foot-binding nowhere more general and more cruel than in this city, and he has ordered fifty thousand copies to be printed for his own distribution. He is about to open a Viceregal college employing European instructors, although this scheme may fall through, as he is once more enacting the old edict ordering all scholars to do reverence before the tablet of Confucius. Already an immense military college is built, where Japanese officers are to train two hundred and fifty Chinese military Mandarins. A yet larger gymnasium for civilians, to be likewise under Japanese instructors, has also been built; Japanese officers have been procured to drill the army, and already from wall to wall and from Yamen to Yamen long-drawn melancholy trumpet notes wail out the difficulties of Chinese bandsmen, struggling with European reveilles and tattoos. The Viceroy threatens to get the city cleaned out. He has already made it safe, and he found it almost in the hands of the Boxers, so slack had everything grown under the rule of the late Viceroy, an amiable Manchu, named Kuei. At the fires that have lately, occurred, one a week, in the business parts of the city, the Viceroy himself has been out at night in an open sedan, so that he could see all round at once, enforcing order and keeping local careless officialdom up to the mark. It is sad to say that a young Englishman saw one of these sleepy ones, roused by an attentive servant as the Viceroy drew near, at once compose himself to sleep again

as his chief passed on his rounds of inspection. By day the Viceroy was at the smoking ruins again, on horseback this time. A man caught stealing was at once beheaded, his head stuck in a cage on a pole, and there it still is.

Cages are put to all sorts of uses here; heads put into them are stuck up high, of course, so that everyone may see them. And one can know where they are by seeing men quickly pulling their ample sleeves over their mouths and noses as they glance upwards. Prisoners also are placed in cages, sometimes in such that they can neither lie nor sit. Cats are habitually carried about for sale in cages in a land where goats spring about muzzled and haystacks float down great rivers. Dogs also at the festive season of the Chinese New Year are carried about in cages, barking somewhat indignantly. When I travelled through the west of China in a particularly comfortable basket chair, on which one could on occasion sleep at ease, the little boys used to cry out: "Look at the foreign woman in a cage!" And when some thieves drugged us by burning something and ransacked our bedroom while we slept, those same thieves were made to stand up in cages for days outside the door of our house, as a warning to others. Thus cages have many uses besides that of taking birds out for airings as we take our dogs.

But with all this hospitable reception of all the foreign men here at a dinner in the foreign style, his encouraging answer to the united missionary greeting, and apparent general enlightenment, deep within him the Viceroy Tsên must have stuff we little understand. He is the son of that Tsên in whose Viceroyalty of Yunnan Margary was murdered. When the British Minister of those days was most determined to obtain fitting expiation for the cruelly treacherous murder of this most brilliant young Consular official, the