posed. One of my tubes cast distinct double shadows, the stronger shadow falling in a direction as if the rays had come straight from the cathode, the fainter shadow in a direction straight from the phosphorescent patch on the glass. Interposing a piece of pine-wood, I have found shadows of the grain of the wood upon the sensitive plate, which proved that the dark resinous streaks are more transparent to these rays than the lighter-colored tissue. I have obtained shadows of coins shut up in a leather purse, of pens inclosed in a wooden box, of a pair of spectacles lying in its case, and of gems of various sorts inclosed in a wooden box. Olivine appears to be more opaque than topaz, sapphire, or diamond. Diamond is more opaque than black carbon of equal thickness. A piece of amber inclosing flies shows no shadows of the flies. I have found no difficulty in getting shadows of the bones of the hand, even down to the wrist; but in my sciographs, as in those of Mr. Swinton, the flesh always casts a shadow also. Magnetized iron and non-magnetized iron appear to be equally opaque. Bones are not very opaque: one notices in the shadows of the carpal bones of the hand that the enlarged ends, where there is marrow, are more transparent than the parts where the bone is denser. At present there is not the slightest evidence that these rays can be polarized; that is the strongest argument in favor of the view that they consist of longitudinal vibrations. Neither, as yet, has any means been found of reflecting them. They apparently agree with ultra-violet light in one respect only, that of frequency. But of their wave-length, whether it is shorter or longer than that of ultra-violet light, nothing is certain. It depends on the velocity of propagation of the rays as to whether it is less or greater. The name of "ultra-violet sound» appears to me to be appropriate to the phenomenon. The thing most wanted now is a more powerful means of exciting the rays so as to shorten the time of exposure.

I find that metallic sodium is more transparent than metallic potassium, and slightly more transparent than aluminium. Metallic lithium is far more transparent than either. It is certainly ten times more transparent than aluminium, and can hardly be caused to cast any shadow at all. In fact, it appears as though the opacity of bodies to the Roentgen rays was proportional, not to density, but to atomic weight. Imitation rubies made of red glass are more opaque than natural rubies; imitation pearls are more opaque than real pearls. To obtain good sciographs of hands

VOL. LII.-17.

and feet, showing the bones only, a longer exposure is needed than will suffice to show the bones through the flesh. With prolonged exposure the flesh disappears, the rays penetrating it more and more.

The negatives frequently show as though much more fully exposed on the side next the glass than on the front of the film. This gives color to the notion that the photographic effect is of a secondary order, the Roentgen rays penetrating the film to the surface of the glass, where by some transmutation akin to phosphorescence they generate the photographic effect. Abney says that if the sensitive films are spread on ferrotype iron instead of on glass no shadows are produced. The statement attributed to me in various quarters, that I have found Roentgen rays in the arc-lamp, has never been made by me. What I have found is that, using an arc-lamp, I could get photographic shadows of metal objects through a wooden screen; but they are stopped by an aluminium sheet, and hence are not due to Roentgen rays.

I have succeeded in reading the contents of a sealed letter by the Roentgen method. The ink was of a metallic nature; writing in vegetable inks produces no appreciable shadow.

In the sciograph of the hand of a child aged eleven, in St. Bartholomew's Hospital, London, suffering from growth of bony tumors upon the bones of hands, feet, etc., the distortions of the joints so produced are very plainly shown.

Silvanus P. Thompson.

CITY OF LONDON AND GUILDS TECHNICAL
COLLEGE, LONDON, ENGLAND.

AT the University of Toronto, as elsewhere, the announcement by Professor Roentgen of his discovery of a new form of radiation excited the most intense interest. Together with Mr. C. H. C. Wright and Mr. Keele of the School of Practical Science, I arranged a series of experiments to verify, if possible, the results said to have been obtained. Although we were successful in establishing the extraordinary penetrating power of the rays and their action on a sensitized photographic plate, we found that long exposures were necessary in order to obtain sharp and clearly defined images. As this limited to a very great extent the applications of the "new photography,» we directed our efforts to reducing, if possible, the time of exposure, and this we succeeded in doing to a very marked degree.

On making a careful test of all the tubes in the physical laboratory, we found one which

gave a much stronger radiation than any of the others. This tube was pear-shaped, and as it had one electrode inserted in the smaller end and the other in the side, we were able, by making the former the negative terminal, to obtain a large glass surface exposed to the action of the cathode rays. This tube was employed in all our later experiments. Thinking that probably the action would vary with different sensitized films, we conducted tests to determine the relative sensitiveness to the rays of various types of plates; but we observed marked difference, and concluded that any reduction in the time of exposure must be otherwise obtained. Experiments were also made with prisms and lenses of wood, pitch, and other materials, but no indication of refraction at their surfaces could be discovered.

The only remaining method for the concentration of the rays seemed to be an application of the principle of reflection. In order to determine whether the rays could be reflected, a surface of clean mercury was prepared, and it was found that when the rays were directed towards this sensitized films protected from direct radiation were fogged by some action coming from the mercury. To test this apparent reflection still further, a sensitized film, protected by a plate-holder, was placed at a distance of about twenty centimeters below the Crookes tube. A thick plate of glass was then inserted midway between the tube and the film, parallel with the latter, with the intention of screening the plate in part from the action of the rays. The tube was then excited for some time, and on developing the film it was found that the rays evidently traveled in straight lines, since the part of the film protected by the glass plate was well defined and entirely unaffected by them. This experiment was repeated, the arrangement of apparatus being identical, with the sole exception that a glass bell-jar was placed over the whole. Development of the film in this case showed (1) no action on the film outside the jar; (2) no indication that the interposed glass plate acted as a screen; (3) the action much more intense than in the previous experiment, proving conclusively the reflection of the rays from the surface of the jar.

By the employment of this method we reduced on February 11 the time of exposure almost to instantaneousness. The picture of the pendant given on page 121 was taken with the bell-jar over the apparatus, and was obtained by an exposure of four and a half seconds, the object being a medal placed within a leather

ALL about and within us exist rates of vibration known as forms of energy, some of them forced by man's ingenuity to record themselves by aid of mechanisms, others yet awaiting this sort of detection. Recording devices to reveal laws of light, heat, or chemical affinity are familiar, but no one has in a similar manner recorded thought or gravitation. Electricity yields its secrets slowly. While Faraday divined and Maxwell proved mathematically its existence outside of the conductor, Hertz actually detected its vibration and its wave-lengths by means of his oscillator. Lenard detected and recorded cathodic rays outside of a vacuum-tube, and now Roentgen comes forward to show by a device that the leather of a purse and the flesh of the hand may be penetrated by a radiation, leaving coins within, and bones otherwise invisible, pictured. At once man's curiosity in uncovering the otherwise unseen became highly excited.

Reference to one's own personal participation in the development of the Roentgen process even now seems like a reminiscence, so rapidly have events moved onward. The announcement of its possibility found me fully equipped with all needful electrical apparatus, except a Crookes tube, which could not be purchased anywhere. I therefore turned my attention at once to the static machine and ordinary vacuum-bulbs, and with these simple appliances have progressed to a point of picturing all sorts of metallic objects upon six-inch by eight-inch, or even larger plates, in from three to five minutes, and have obtained a perfect shadowgraph of a small piece of a needle behind a bone in the foot. The bones of the hand have already become an old story. I find my X rays are very intense, so much so that over-exposure easily penetrates some bones and thin plates of metal.

My first experiments demonstrated that shadowgraphs could be obtained simply by causing a powerful spark from the static machine to pass around, but not through the plate-holder. One of my first working vacuumbulbs was a radiometer such as is commonly sold by opticians, to which I attached external electrodes. Another form of vacuum-bulb had one external and one internal electrode. The illustration on page 125 represents an early effort with the radiometer bulb. I now use some bulbs a foot in diameter and having no enter

My experiments with the Roentgen rays have been almost entirely devoted to investigating the phenomena with a view to obtaining the most practicable and powerful form of apparatus especially the fluorescent lamp, the photographic plates, and the best form of electric oscillation to energize the lamp. Having all the appliances for working with incandescent-lamp vacua, I have been enabled to try a large number of experiments with this end in view. I have not as yet attempted to take pictures other than a standard figure of a number of bars of metal, bone, etc., on cardboard.

I am now fitting up a complete apparatus, and expect soon to conduct a number of accurate experiments in the photography of animate and inanimate objects. From the rough experiments recorded in my note-book Ibrief the following:

1. The ray proceeds from all parts of the glass illuminated by fluorescence.

2. With the same degree of fluorescence, the effect is independent of the size or position of electrodes.

3. Under the same conditions as to the distance of the lamp from the plate, the distortion increases with the increase in the size of the lamp-bulb.

4. Records taken every three inches up to

thirty-six inches show that the photographic effect of the ray diminishes as the square of the distance, as stated by Roentgen.

5. Commercial dry plates vary much in their sensitiveness to the ray. The most rapid plates for light are the slowest for the ray.

6. As nearly as can be ascertained at present, the power of the ray to photograph varies as the square of the illuminating power of the fluorescence.

7. The phosphorescence of the lamp after the current is stopped does not photograph. Powerful after-phosphorescence of a lamp is no indication of its value for photographic work.

8. High vacuum diminishes fluorescence and the sensitiveness to photographic work. The point of maximum fluorescence is where the residual gases just perceptibly glow.

9. Fluorescent lamps with aluminium electrodes gradually change to higher vacuum, with diminishing fluorescence and consequent lower sensibility. Gentle heating of the lamp restores the absorbed gases temporarily.

10. The smaller the lamp the less will be the distortion of the shadow, and the closer can the plate and the lamp be placed, thereby increasing the sensibility greatly.

11. Substances so far tried which powerfully phosphoresce in the bulb of the lamp do not photograph when phosphorescent after the current is stopped.

12. Heating the dry plate does not appreciably increase its sensitiveness.

13. A good lamp should give a clear photograph of thin metallic strips through eight inches of Georgia pine in fifteen minutes.

RINCE MICHAEL of Polkavia is a charming young man. His territory is one of the small independent states of the Balkan Peninsula; but you will search in vain for it upon the maps, even those war maps which make a strategical point of every mole-hill. He is bon prince, and lets his subjects do pretty much as they like, while he amuses himself in the pleasure resorts and the capitals of Europe, with a run now and then to Cairo or Constantinople. Indeed, I do not believe that his diversions are very reprehensible; there is in him a strong dose of ideality which restrains him from vulgar escapades.

The prince has hazel eyes that are rather dreamy; soft blond hair; and a waist slender, like that of a young girl; his manners are delightfully easy, with a childlike frankness which may be the last touch of his diplomatic training. Now and then a fine smile illumines the small red mouth under his carefully pointed and waxed mustache. One has heard women, by no means school-girls, declare that they became fond of Prince Michael from the moment when he was presented, and, standing before them, clicked together the high heels of his varnished boots, and executed a bow which, while wholly modern, yet appeared to include the antique homage of the days of the minuet, even of the times of medieval chivalry. Moreover, it is said that the prince does not lack courage, is a fearless rider, and very expert as a swordsman. He also speaks fluently at least half a dozen languages.

Is Prince Michael then perfection? Alas! the justice of contemporary biography is obliged to admit that this pearl has a flaw: Prince Michael is deeply tinged with romanticism, a quality with which this end of the century does not know what to do. In the mingled races of the Balkan are strangely assorted characteristics, which set off one another by force of contrast. Prince Michael knows his Paris, his Vienna, his St. Petersburg, and one fears that he is not unaware of his Monte Carlo; but he is dominated by a fixed idea, incredibly fantastic, which has hindered him in the choice of a bride: he adores nothing so much as small, even microscopic feet. And of all the demoiselles of high descent and

of fortune who were proposed for him in court circles not one had the sort of feet at which he could prostrate himself and sigh as he would have wished to do.

Not devoid of a smattering of the classics and gifted with a very pretty taste in composition, Prince Michael is author of a brochure on the comparative mythology of the famous nursery tale of Cinderella and the Greek legend of Rhodope. A copy of this treatise, elegantly printed between slip covers of blueand-silver brocade, is a graceful gift to such acquaintances as the prince chooses to admit to a certain degree of friendship. He was so good as to present one of them to me because after the incident was closed I told him—

But instead this is the beginning of the anecdote. It all happened in the city of Catania and upon Mount Etna, whose majestic gloom ought to have been an effectual rebuke to so much frivolity.

At the table d'hôte of the Albergo Orientale the prince had begun an acquaintance with our small party-one of those passing relations of tourists without consequences. It amused Prince Michael, and he vowed that it was instructive to get the American ideas upon things. «You of the United States have a point of view rather original perhaps, but full of good sense,» he opined.

After a few days one had heard all the theories and some judicious selections from the experiences of this young man, who by grace of what Latin blood was in his veins. had preserved a curious naïveté of mind. One was shown the photographs of his august dowager mama and of the princesses Wanda and Helena, his sisters. It seems to me that they traced their lineage back to Charlemagne; undoubtedly the young ladies, who were pictured in the short skirts of the peasant costume of Polkavia, inherited from the Emperor's mother, the famous Bertha Broadfoot. Hence, perhaps, the prejudice of their brother in favor of tiny feet. In showing the photographs, indeed, Prince Michael betrayed some regret.

<«<It must be avowed,» said he, shaking his head sadly, «that my sisters have les pieds énormes.»

You can judge of the sensation experienced one morning by this enthusiast when, as he

passed along the corridor of the floor where he lodged, he beheld in front of a closed door the prettiest, the most microscopic pair of shoes that had ever rejoiced his eyes. They were of russet-colored Russian leather, charmingly polished, waiting to be taken into that chamber whenever the indolent little feet of their mistress should be ready to put them on. "I may have committed an indiscretion,» the prince told me quite gravely. "I confess that I could not refrain from lifting one of those shoes in order to examine it. It was miraculously small, numbered 13 of exquisite proportions, not distorted anywhere by the slightest irregularity of the enchanting foot that it is privileged to contain. J'en suis fou!» he concluded.

"An amiable madness, prince,» said I.

I ought to be chained; I certainly shall commit some folly.»

The greatest folly might be to enchain yourself.>>

That is very true, madame.»>

When finally the owner of the famous shoes appeared one was ready to believe that the prince really might do many a thing more foolish than to make her his princess. She was American-precisely, from New York. Her name was Angelica Van Doren; she was accompanied by her mama, who chaperoned her very conscientiously, although it was evident that the strict system of surveillance was entirely by will of the daughter. Sometimes it seemed as if the elder woman saw little use in so much watchfulness, and would not have disliked a brief vacation in which she might take naps, read novels, and rest her weary feet and mind from sight-seeing; but there is nothing so correct, so inexorable, as a modern girl who brings herself up well, and, incidentally, also her mother.

And truly Miss Van Doren was a nice girl, which in her case means amiable, gay, unaffected, self-possessed, with a reserve fund of common sense to draw upon when occasion should require. We all liked the Van Dorens, and as to the prince, it was quite his own affair. One had no disposition to make or to mar an international alliance. In fact, barring that weak fiber of romanticism, Prince Michael of Polkavia was, and no doubt is, abundantly able to take care of himself.

Every morning those delicious russet shoes stood sentinel before the door of the sleeping Miss Angelica. At a quarter past nine her maid carried them in to meet their happy destiny, to be trodden by her perfect feet. By the way, and we thought it very nice of her, --Miss Angelica never made any display of

her foot; she wore her gowns, indeed, rather long in the skirt, and took none of the careless and ungraceful attitudes which are affected by some women, crossing one ankle over the other. She appeared as nearly unaware of her charms as could possibly be expected of one so very, very pretty. For she was really beautiful, in the rather fragile, high-strung, finely modeled type of American. Her nose was a little masterpiece in ivory; her hair was chestnut, inclined to mutinous curls; her eyes were violet blue, very large and darkly fringed; her hands were not particularly small, but were daintily rounded, with pink nails. Her voice, alas! had certain wiry vibrations when raised, but even these were not wholly unmusical; and her costumes were innumerable and admirable, authentic creations of Doucet, Paquin, and the others.

Prince Michael complained to me of the adorable modesty which caused Miss Angelica to be chary of the view of her feet. «Always veiled in the discreet shadow of her skirts,>> said he. «Once, indeed, in descending a stairway one foot was visible as far as the instep. But-will you credit me?-I, from respect for the chaste sentiments of the young girl, averted my gaze. I remained deprived of the sight, but I am content with myself.>>

Now was there ever anything finer in the days of chivalry than this abnegation of the excellent prince?

It was impossible to judge whether Miss Angelica took the devotion of Prince Michael seriously. American girls are tomed to openly expressed admiration and to «attentions without intentions » that the compassed and rather formal homage of the prince might very well have failed to explain itself to her. At all events, she was quite at ease and companionable with him, precisely as with a young man of her set in New York. She had a very agreeable manner, independent, yet free from pertness; and this republican geniality of hers greatly attracted Prince Michael.

«I foresee, madame,» he told me, «that I shall kneel at her feet.>>

«Always her feet, prince! You say nothing of her face or of her heart.»>

He looked misunderstood. «You know that the foot of a fairy is my ideal,» he answered quite simply.

For several days it had rained; the winds swept back and forth through the Straits of Messina, storming, and the heavens above wept to see them so quarrelsome. Hence our excursion upon Etna had been postponed (a party of a dozen persons had been arranged), and what with the weather, added to a two