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dtor, hale and hearty, overflowing with celebrities here; Poynter getting on. This is a very alth and happiness, had gone to his work jolly little village, and I wish you were over here. the hospital. That night he came home They do make such a fuss with an agreeable

fellow, ood-poisoned, to die in his wife's arms.

like you or me, for instance. I think you would Du Maurier's stay on the Continent came paint here; but if you are getting on so well in

precious soon get more portraits than you could a close some time before mine, and to that Paris, of course it would be madness to leave. But rcumstance I owe several letters in which I do not like the idea of your not being one of us u speaks of his first experiences in London. -such a band of brothers full of jolly faults that He reveled in the metamorphosis he was dovetail beautifully. It was quite a freak of mine undergoing, and illustrated the past and the coming over here; I did it against everybody's ad

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present for my better comprehension. There vice. Came over with a ten-pound note, and made on one side of the Channel he shows the de- the rest. «Your friend Bobtail seems to be the only jected old lion of Mechlin gnawing his to- man who had no doubt of your talent» writes my baccoless clay pipe, and then on the other mother. Enfin c'est prouvé que je suis au moins bon the noble beast stalking along jauntily with à quelquechose. Do you go much into the world? I tail erect and Havana alight. He wrote in go knocking about as happily as possible, singing, high spirits:

and smoking cigars everywhere. Jimmy Whistler and I go « tumbling » together, as Thackeray says.

Would you were here to tumble with us! Enfin, How strange to think of such a change! I'm mon bon, écris moi vite. leading the merriest of lives, and only hope it will last. Living with Henley, No. 85 Newman street;

When at last I too returned to London, I very jolly and comfortable. Chumming with all was privileged to take my humble share in the the old Paris fellows again; all of them going «tumbling, as also in the steady process that ahead. There's Whistler, already one of the great was gradually to wean us from Bohemia.

Felix Moscheles.

wed. I session

:ciola,» PHOTOGRAPHING THE UNSEEN.

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DRAWN BY AUGUST WILL.

A CROOKES TUBE MADE BY

THOMAS A. EDISON.

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scientific history few investigators (some of it recorded in thi'riend-
last year was the issue of THE CENTURY), the vast mass of effor rately
isolation, by two has been mere tiresome repetition of a vn' then,
physicists of Eng- limited number of Professor Roentger distant
land, of a new ele- periments.
ment in the atmo- The detection and utilization of the X. r Pic-
sphere. That dis- was in a sense evolutionary, although th ouple,
covery of argon, actual occurrence was quite by accident. Dat moon.
the unsuspected ing, perhaps, from Hauksbee's Royal Socie Oppor-
existence of which work in obtaining phosphorescent light nalysis
for so long was rubbing briskly a glass globe exhausted ned to
hardly to the air, it was a fashionable amusement throug. - laid
credit of modern out the whole of the last century to witness!
science, is now electrical discharges in

matched by the vacuo. The reader can beautiful work of Professor W. C. Roentgen test the thing for himin photographing the unseen by electric rays self by taking any infrom vacuum-tubes. It cannot be said that candescent lamp into a either of these advances was eagerly awaited dark corner, and chafas a sequential development. On the contrary, ing it briskly with a bit

omple? the individuality of argon was very strenu- of cloth or silk, when he

wild. It ously denied by expert philosophers, and the will see a gleam of blufirst announcement of the «X rays, with their ish light within the curious Paul-Pry capacity for photographing bulb. Of late years through a brick wall, was also met with out- the favorite means spoken incredulity. From such incidents as of studying such these one may fairly infer that, while patient effects has been a investigation will always count for much in Geissler tube of science, happy chance is an important factor. glass, into which, Innumerable eyes are strained in their gaze little wires of platupon the gloom, and just at what moment and inum being sealed at which point the veil of fog may casually lift at each end, highis forever uncertain.

tension currents This country is proverbially alert in matters can be passed, with of discovery, yet it was several days before the help of an inany one repeated the Roentgen experiments, duction-coil. The news of which had been cabled in graphic discharge in the detail by European correspondents. As if to tube across the compensate for the delay and inertness, the space from wire to other extreme has since been rushed to, and wire creates beauno school or college has considered the day tiful effects of colwell spent in which, with endless iteration, it ored light, depenhas not taken « cathodographs » of hands and dent on the nature coins. The sheep-like tendency of human be- of the rarefied ings is once more exemplified in the fact that, gases within the while a large proportion of the inhabitants tube. Professor of the United States have had their hands Crookes followed «taken, only a single foot, so far as the writer up this line of work is aware, has been made to reveal the secrets by improving such

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DRAWN DY AUGUST WILL.

ANOTHER FORM OF CROOKES TUBE

MADE BY THOMAS A. EDISON.

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der 5, and by his brilliant demonstrations in fluence, but they refuse to be reflected, and doc be 1 of matter in the fourth, or « radiant,) go through various prisms without any sort of ite, of which Faraday spoke eighty years apparent refraction. They persist in follow10. From these experiments by Crookes ing absolutely straight lines, starting from. ted new phenomena of phosphorescence the point on the glass bulb that is seen to be to

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 obY CATHODOGRAPHED THROUGH A BOOK OF 526 PAGES Some trustworthy experimenters find the rays

viously suggest that they may engender heat. IN THE CHEMICAL DEPARTMENT, U.S. MILITARY ACADEMY, WEST POINT, N. Y.

peculiarly irritating to the eye, and others

have been making suggestive experiments to and fluorescence created by electric ac- prove the similarity of these subtle emanaLion. When the current is passed into a va- tions with non-luminous ultra-violet portions cuum-tube which has wires or disks sealed of the spectrum, to which the word « light » into each end or side walls, the glow, starting is not usually applied. from the positive, or anode, tip, fades out as The electrical conditions involved are of init approaches the negative, or cathode, end. terest by themselves, and hence the energy Around the cathode exists a dark space, a of investigation is now concentrating upon "e No Ray Land, or buffer state, at the them. The most striking of the new results

redge of which the deep violet radiations is that announced by Professor J. J. Thomcrly die out. Just what the conditions are, son, who discovers that the Roentgen rays and just what happens in the dark cathode dissipate the electrostatic charge of any subregion, seems uncertain, but the subject has stance upon which they fall, no matter how been deeply investigated, and Professor Roent- the body may be protected against discharge. gen's discovery is one fruit of exploration in From this the writer would infer that the that mysterious auroral territory.

Roentgen rays are those which, on emerging It was first pointed out by the late Profes- from their prison of glass or aluminium, have sor Hertz of Germany that these ultra-violet lost their own electric charge, perhaps enrays from the cathode could penetrate opaque tirely. Professor Thomson states, moreover, bodies, such as aluminium, in a vacuum. This that the nature of the charge, whether posiwas 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.

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.

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tive or negative, is immaterial. The corollary ing the high-tension electricity necessary for drawn by him from this is that all bodies its excitation. At the start the bulb is full of under the influence of these rays become con- air, and as soon as the coil is set in action ductors. One such fact indicates many pos- crooked blue sparks pass freely between the sibilities in the electrical arts and sciences. aluminium plates within. The pump is now

There is no need now to dwell upon the used, the silvery fluid alternately rising and value of the Roentgen rays in surgery and falling within its tubes, and driving out the dentistry, for the newspaper press of Europe air before it. With its first stroke we observe a and America has been full of their use in re- change in the bulb. The blue sparks cease, and vealing the condition of the bony structure of in their place appears a waving purple flame, the body. Their employment in the testing which, as the air becomes rarer, broadens

, of metals, the inspection of objects in closed and finally breaks up into stratifications. The or concealed packages, and the detection of room is now darkened. Little disks of bluishdifferences in various substances, is obvious. white light fill the tube, resembling somewhat One immediate and important application al- a pile of saucers. The spaces between them ready made on both sides of the Atlantic is widen, and finally a dark space appears about to the study of moving objects projected on one of the electrodes. The discharge is now

. a fluorescent screen, while yet another inven- approaching the form described by Crookes as tion is aimed at seeing and photographing «radiant, the light becomes fainter, and the objects hidden by darkness.

dark space widens out until it touches the It will conduce much to the utility of these glass wall, which instantly glows with its rays, however, to determine, first of all, their characteristic green phosphorescence. A few nature; that is, whether they are simply more strokes of the pump and the vacuum is streams of matter under electrical impulse, practically perfect. The resistance to the or light of short wave-length, or some new passage of the current is now so great, and phenomenon of vibration in the ether itself. the potential on the wires rises to such a

point, that purple fringes of electric fire spring Thomas Commerford Martin. forth into the air. Sparks occasionally leap Evrtor of "The ELECTRICAL ENGINEER.) about the outside of the bulb, preferring the

A LIVE MOUSE. (UNDER CHLOROFORM.) CATHODOGRAPH MADE BY DR. KAUFMAN, BERLIN UNIVERSITY. On entering the room in which are arranged long air-gap to the shorter but vacuous one the elaborate paraphernalia necessary for the within. The entire inner surface shines with production of the Roentgen phenomena, the a pale emerald light, while directly in front self-acting mercurial air-pump, with its laby- of one of the disks is a very bright spot of a rinth of tubes and bulbs, is the first object yellowish color, where the full force of the that attracts notice. Connected with this by cathode rays falls. This spot is the source of a slender tube is the small glass bulb, with the mysterious «X rays,» which, though units two electrodes of aluminium, which is the seen, radiate from it in all directions like source of the new energy; while just below it light. is the huge Ruhmkorff induction-coil, furnish- The bulb is now covered with a thick black

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cloth to shut in the green phosphorescent entire surface of the screen shines with a light, which would interfere with the obser- bluish-green light. Placing a few coins in the vation of the phenomena, and the room be- center of a thick book, we hold it between the comes absolutely dark. A large wooden screen and the apparatus. The coins instantly screen, one side of which has been painted appear as circular black shadows on the lumiwith barium platinocyanide, is set up before nous background. A brass stencil-plate is the bulb, with its coated side toward us. The placed in an aluminium cigarette-case and invisible rays, passing through the board, ex- held against the screen. The light metal is cite fluorescence in the barium salt, and the more transparent to the rays than the dense,

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