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dtor, hale and hearty, overflowing with alth and happiness, had gone to his work the hospital. That night he came home ood-poisoned, to die in his wife's arms. Du Maurier's stay on the Continent came a close some time before mine, and to that rcumstance I owe several letters in which speaks of his first experiences in London. He reveled in the metamorphosis he was undergoing, and illustrated the past and the
celebrities here; Poynter getting on. This is a very jolly little village, and I wish you were over here. They do make such a fuss with an agreeable fellow, like you or me, for instance. I think you would paint here; but if you are getting on so well in precious soon get more portraits than you could Paris, of course it would be madness to leave. But I do not like the idea of your not being one of us -such a band of brothers full of jolly faults that dovetail beautifully. It was quite a freak of mine coming over here; I did it against everybody's ad
present for my better comprehension. There on one side of the Channel he shows the dejected old lion of Mechlin gnawing his tobaccoless clay pipe, and then on the other the noble beast stalking along jauntily with tail erect and Havana alight. He wrote in high spirits:
How strange to think of such a change! I'm leading the merriest of lives, and only hope it will last. Living with Henley, No. 85 Newman street; very jolly and comfortable. Chumming with all the old Paris fellows again; all of them going ahead. There's Whistler, already one of the great
vice. Came over with a ten-pound note, and made the rest. «Your friend Bobtail seems to be the only man who had no doubt of your talent,» writes my mother. Enfin c'est prouvé que je suis au moins bon à quelquechose. Do you go much into the world? I go knocking about as happily as possible, singing,
and smoking cigars everywhere. Jimmy Whistler and I go «tumbling » together, as Thackeray says. Would you were here to tumble with us! Enfin, mon bon, écris moi vite.
When at last I too returned to London, I was privileged to take my humble share in the "tumbling,» as also in the steady process that was gradually to wean us from Bohemia.
DRAWN BY AUGUST WILL.
PHOTOGRAPHING THE UNSEEN.
A SYMPOSIUM ON THE ROENTGEN RAYS.
A CROOKES TUBE MADE BY
THOMAS A. EDISON.
THE most notable event in scientific history last year was the isolation, by two physicists of England, of a new element in the atmosphere. That discovery of argon, the unsuspected existence of which for so long was hardly to the credit of modern science, is now matched by the beautiful work of Professor W. C. Roentgen in photographing the unseen by electric rays from vacuum-tubes. It cannot be said that either of these advances was eagerly awaited as a sequential development. On the contrary, the individuality of argon was very strenuously denied by expert philosophers, and the first announcement of the « X rays,» with their curious Paul-Pry capacity for photographing through a brick wall, was also met with outspoken incredulity. From such incidents as these one may fairly infer that, while patient investigation will always count for much in science, happy chance is an important factor. Innumerable eyes are strained in their gaze upon the gloom, and just at what moment and at which point the veil of fog may casually lift is forever uncertain.
This country is proverbially alert in matters of discovery, yet it was several days before any one repeated the Roentgen experiments, news of which had been cabled in graphic detail by European correspondents. As if to compensate for the delay and inertness, the other extreme has since been rushed to, and no school or college has considered the day well spent in which, with endless iteration, it has not taken « cathodographs » of hands and coins. The sheep-like tendency of human beings is once more exemplified in the fact that, while a large proportion of the inhabitants of the United States have had their hands "taken, only a single foot, so far as the writer is aware, has been made to reveal the secrets
talent t, once
of its flesh-clad anatomy. It is even more reisband markable that, outside of the work done by tation few investigators (some of it recorded in thi riendissue of THE CENTURY), the vast mass of efforrately has been mere tiresome repetition of a v then, limited number of Professor Roentger periments.
mple. ild. It
The detection and utilization of the X. was in a sense evolutionary, although thouple, actual occurrence was quite by accident. Dat moon. ing, perhaps, from Hauksbee's Royal Socie opporwork in obtaining phosphorescent light nalysis rubbing briskly a glass globe exhausted ned to air, it was a fashionable amusement throug.. laid out the whole of the last century to witness electrical discharges in vacuo. The reader can test the thing for himself by taking any incandescent lamp into a dark corner, and chafing it briskly with a bit of cloth or silk, when he will see a gleam of bluish light within the bulb. Of late years the favorite means of studying such effects has been a Geissler tube of glass, into which, little wires of platinum being sealed at each end, hightension currents can be passed, with the help of an induction-coil. The discharge in the tube across the space from wire to wire creates beautiful effects of colored light, dependent on the nature of the rarefied gases within the tube. Professor
Crookes followed up this line of work by improving such
DRAWN BY AUGUST WILL.
ANOTHER FORM OF CROOKES TUBE MADE BY THOMAS A. EDISON.
do 5, and by his brilliant demonstrations in he of matter in the fourth, or "radiant,» te, of which Faraday spoke eighty years 0. From these experiments by Crookes ted new phenomena of phosphorescence
fluence, but they refuse to be reflected, and go through various prisms without any sort of apparent refraction. They persist in following absolutely straight lines, starting from. the point on the glass bulb that is seen to be faintly fluorescing with a blue-green light, under the action of the invisible rays from the cathode to the glass. While they present analogies with the ultra-violet rays of the spectrum, their close identity with light is still regarded as doubtful. Light is attributed to transverse vibrations of the ether, but Professor Roentgen has suggested that his rays may be longitudinal vibrations, like soundpulses in the air. They do at least throw shadows, cause chemical action, and set up fluorescence, while the last fact would obviously suggest that they may engender heat.
"Y CATHODOGRAPHED THROUGH A BOOK OF 526 PAGES Some trustworthy experimenters find the rays
nd fluorescence created by electric acion. When the current is passed into a vacuum-tube which has wires or disks sealed into each end or side walls, the glow, starting from the positive, or anode, tip, fades out as it approaches the negative, or cathode, end. Around the cathode exists a dark space, a "e No Ray Land, or buffer state, at the redge of which the deep violet radiations rly die out. Just what the conditions are, and just what happens in the dark cathode region, seems uncertain, but the subject has been deeply investigated, and Professor Roentgen's discovery is one fruit of exploration in that mysterious auroral territory.
It was first pointed out by the late Professor Hertz of Germany that these ultra-violet rays from the cathode could penetrate opaque bodies, such as aluminium, in a vacuum. This was interesting, but Dr. Philip Lenard further showed that such rays would also pass out into the air and through any substance lying beyond the vacuum. They would travel a considerable distance, would cause phosphorescence, and would act on photographic plates. From this to the discovery of Roentgen, who has caused the permeable substances interposed in the lines of these rays to register their shadows on a photographic plate, is but a step, though a long and memorable one.
peculiarly irritating to the eye, and others have been making suggestive experiments to prove the similarity of these subtle emanations with non-luminous ultra-violet portions of the spectrum, to which the word «light » is not usually applied.
The electrical conditions involved are of interest by themselves, and hence the energy of investigation is now concentrating upon them. The most striking of the new results is that announced by Professor J. J. Thomson, who discovers that the Roentgen rays dissipate the electrostatic charge of any substance upon which they fall, no matter how the body may be protected against discharge. From this the writer would infer that the Roentgen rays are those which, on emerging from their prison of glass or aluminium, have lost their own electric charge, perhaps entirely. Professor Thomson states, moreover, that the nature of the charge, whether posi
At this moment discussion is rife as to the nature of the Roentgen ray, and many old theories as to light, electricity, and the ether are threatened with change. The obedience of the ordinary cathode rays to a magnet is one of their characteristics; but the X rays are still Bezonians whose king is unknown, for PENDANT AND PIN IN A BOX. CATHODOGRAPH MADE IN they not only do not respond to magnetic in- 4% SECONDS AT THE TORONTO UNIVERSITY. (SEE P. 130.) VOL. LII.-16.
tive or negative, is immaterial. The corollary drawn by him from this is that all bodies under the influence of these rays become conductors. One such fact indicates many possibilities in the electrical arts and sciences. There is no need now to dwell upon the value of the Roentgen rays in surgery and dentistry, for the newspaper press of Europe and America has been full of their use in revealing the condition of the bony structure of the body. Their employment in the testing of metals, the inspection of objects in closed or concealed packages, and the detection of differences in various substances, is obvious. One immediate and important application already made on both sides of the Atlantic is to the study of moving objects projected on a fluorescent screen, while yet another invention is aimed at seeing and photographing objects hidden by darkness.
It will conduce much to the utility of these rays, however, to determine, first of all, their nature; that is, whether they are simply streams of matter under electrical impulse, or light of short wave-length, or some new phenomenon of vibration in the ether itself.
Thomas Commerford Martin.
EDITOR OF THE ELECTRICAL ENGINEER,»
ing the high-tension electricity necessary for its excitation. At the start the bulb is full of air, and as soon as the coil is set in action crooked blue sparks pass freely between the aluminium plates within. The pump is now used, the silvery fluid alternately rising and falling within its tubes, and driving out the air before it. With its first stroke we observe a change in the bulb. The blue sparks cease, and in their place appears a waving purple flame, which, as the air becomes rarer, broadens, and finally breaks up into stratifications. The room is now darkened. Little disks of bluishwhite light fill the tube, resembling somewhat a pile of saucers. The spaces between them widen, and finally a dark space appears about one of the electrodes. The discharge is now approaching the form described by Crookes as «radiant,» the light becomes fainter, and the dark space widens out until it touches the glass wall, which instantly glows with its characteristic green phosphorescence. A few more strokes of the pump and the vacuum is practically perfect. The resistance to the passage of the current is now so great, and the potential on the wires rises to such a point, that purple fringes of electric fire spring forth into the air. Sparks occasionally leap about the outside of the bulb, preferring the
CATHODOGRAPH MADE BY DR. KAUFMAN, BERLIN UNIVERSITY. long air-gap to the shorter but vacuous one within. The entire inner surface shines with a pale emerald light, while directly in front of one of the disks is a very bright spot of a yellowish color, where the full force of the cathode rays falls. This spot is the source of the mysterious «X rays, which, though unseen, radiate from it in all directions like light.
A LIVE MOUSE. (UNDER CHLOROFORM.) ON entering the room in which are arranged the elaborate paraphernalia necessary for the production of the Roentgen phenomena, the self-acting mercurial air-pump, with its labyrinth of tubes and bulbs, is the first object that attracts notice. Connected with this by a slender tube is the small glass bulb, with its two electrodes of aluminium, which is the source of the new energy; while just below it is the huge Ruhmkorff induction-coil, furnish
The bulb is now covered with a thick black