Reprinted from the New YorTc Medical Journal 
for April 25, 1896. 
AN ABSTRACT OF A LECTURE ON THE 
NEW RAYS OF RONTGEN, THE NEW PHOTOGRAPHY, 
AND THE PHOTO-FLUOROSCOPE; 
THEIR JOINT APPLICATION IN MEDICINE. 
Delivered before the Medico-legal Society, April 15, 1896. 
By J. MOUNT BLEYER, M. D., F. R. A. M. S., 
MEMBER OP THE SOClflTE FR ANQAISlTb"OTOLOGIE, DE LARYNGOLOGIE, ETC., 
PARIS, ETC. 
[After a few introductory remarks, Dr. Bleyer spoke substantially 
as follows:] 
Allow me to call your attention to some early work 
on the invisible rays. It is known that the force which 
we call light is not a tangible entity that we can lay hold 
of like a piece of wood; it is a very rapid wave motion or 
vibration of a hypothetical medium called the luminiferous 
ether, which motion, communicated to the retina, gives rise 
to a sensation which we call light. 
We are accustomed to speak of substances as being 
opaque, translucent, or transparent, but these terms are not 
absolute by any means, as will be seen from the following 
statement : A sheet of gold of, say, an eighth of an inch 
thickness appears to us to be opaque—that is, we can not 
Copyright, 1896, by D. Appleton and Company. 2 
KONTGEN RAYS AND THE PHOTO-ELUOROSCOPE. 
see through it; ordinary glass, on the other hand, we can 
see through. But reduce the gold to a thin leaf by rolling 
and hammering, and it 
allows light to pass 
through; increase your 
glass to a very great thick- 
ness and it becomes ab- 
solutely opaque, or allows 
no light to pass. 
We speak of daylight 
as white light, but if a 
narrow slice of daylight 
is allowed to fall upon a 
prism, we obtain a band 
of colors, ranging from a 
deep crimson red, through 
orange, yellow, green, and 
blue, to violet, which 
band is called the spec- 
trum. When sunlight or 
daylight is examined in 
this way, the spectrum is 
found to be crossed by 
numerous transverse dark lines, which may be popularly 
described as landmarks or milestones. Of such a com- 
paratively finite nature is our sight or brain that we can 
only discern a very small portion of the spectrum ; that is 
to say, as long as the vibratory motion lies within certain 
limits we are sensible of the same as light, but at either 
end beyond these limits stretch fields utterly away from our 
visual sensations, but they can be detected by other means, 
such as photography. 
In the spectrogram of the spectrum of cadmium (Fig. 
1), as made by J. W. Gilford, of London, we have a repro- 
Fig. 1.—Spectrogram of the spectrum of 
cadmium (from the Photogram). RONTGEN RAYS AND TIIE PIIOTO-FLUOROSCOPE. 
3 
duction of a photogram of the spectrum. This illus- 
tration shows that the only portion which can be seen 
by us is that part lying between A and H. It has 
been demonstrated that there are vibrations or waves 
far beyond this origin, as is shown by photography. 
In this region beyond H, or the violet, it stretches 
at least nine or ten times as far; how much farther we 
can not say. Langley’s spectrum, which he made by 
means of his bolometer, shows us the red at one end, 
and in the infra or invisible red region an extension of 
fourteen times the length of the visible spectrum, as seen 
in Fig. 1. 
Professor Langley, of the Smithsonian Institution, has 
given us some very valuable information in regard to the 
spectrum of invisible light by his most ingenious invention, 
the bolometer. This device, as used by him, consists of 
an instrument for measuring minute differences of radiant 
heat by changes in the electric resistance of a blackened 
conductor exposed to it. It consists of a series of plates 
of metal connected with a battery and a galvanometer, to 
the latter being attached a very minute concave mirror, on 
to which is thrown a narrow pencil of light. When the 
spectrum falls upon the blackened surface connected with 
the metal plates, the electric resistance is changed, the gal- 
vanometer is deflected, and the spot of light reflected from 
the concave mirror, which is hung upon a very fine quartz 
fibre, is received upon a photographic plate. On develop- 
ment, a figure like the chain of mountains shown in Fig. 2 
above the spectrum is obtained, from which the line spec- 
trum (called a holograph) is constructed. The theory is 
that where the infra-red spectrum falls there is a develop- 
ment of heat, but where the Fraunhofer lines occur there 
is no heat, and therefore there is a deflection of the spot of 
light. With the bolometer it is possible to measure a dif- 4 
RONTGEN RAYS AND THE PHOTO-FLUOROSCOPE 
ference of heat of a hundred-thousandth of a degree of 
Fahrenheit’s thermometer scale.* 
Fie. 3—Langley’s latest spectrum. The white portion on the left is the visible spectrum, the shaded portion on the 
right representing the invisible or infra-red (from the Photogram). 
Fig. 2.—Langley’s normal bolometric spectrum, showing curves of galvanometer deflections (from the Photogram). 
* E. J. Wall, F. R. P. S. Invisible Rays. London. RONTGEN RAYS AND THE PIIOTO-FLUOROSCOPE. 
5 
In experiments made by the late Professor Tyndall, in 
his most popular lectures at the Royal Institution, he con- 
centrated the invisible red rays from an electric lantern, 
and in their focus fused and burned many metals. Cap- 
tain Abney also photographed, in an absolutely dark room, 
a kettle of boiling water, by the same infra red rays. 
The close connection between light and electricity has 
long been known, for Clerk Maxwell enunciated, the theory 
that light itself was but an electro-magnetic phenomenon, 
and that what we called waves of light were not mechani- 
cal waves at all, but were immensely rapid electric displace- 
ments taking place in the all-pervading ether of space; and 
Professor Sylvanus Thompson states it as his opinion that 
with further developments of the theory it would be found 
to satisfactorily explain all the phenomena of light. That 
electricity generates light or vibratory wave motion is, of 
course, common knowledge, and that electricity is itself 
but a wavelike motion has been shown by the classic ex- 
periments of Hertz, who proved still further the similarity 
of electricity to light by reflecting and refracting the waves 
of electricity he generated just as if they had been light- 
waves. 
We can not see electricity, and we can not see the 
ultra-violet and infra-red rays, but we can prove the exist- 
ence of the same by very easy experiments. In the case of 
electricity, the famous researches of Hertz have placed the 
existence of these electrical waves beyond doubt; the ex- 
istence of the infra-red light waves has been proved not 
only by photography, but also by Professor Langley’s 
bolometer, and the results obtained by this as well as by 
photography in the ultra-violet. 
Besides, however, these waves or rays, there are others 
directly connected with the phenomena of electricity which 
become distinctly visible under certain conditions. If we 6 
RONTGEN RAYS AND THE PIIOTO-FLUOROSCOPE. 
take a glass tube and pass a wire through each end and 
close the ends up, and then draw the air off by a fine aper- 
ture so as to leave, as far as we can, very little or no air 
remaining, we have what is known as a Crookes’s tube; and 
on passing a current of electricity through this, we obtain 
some striking phenomena. For instance, from the anode, 
or positive pole, of the battery, induction coil, or static 
machine supplying the current, we have a series of beauti- 
ful striations or striae of light, which vary in color with the 
gas, a small residuum of which remains in the tube. These, 
however, have but little interest to us. From the cathode, 
or negative pole, proceeds a stream of rays which have 
some extraordinary properties, and have received the name 
of “ cathode rays.” In the first place, these cathode rays 
cause the most brilliant phosphorescence even in glass, but 
on certain well known chemical products the light is ex- 
tremely brilliant, and it is possible, by the interposition of 
screens or patterns cut to a particular shape, to obtain 
sharp, clear-cut shadows of the patterns. Further than 
that, if a series of light vanes or paddles is mounted on an 
axis inside of these tubes, they will rapidly rotate like the 
well-known radiometer or light mill. Then, again, these 
cathode rays have the property of passing through thin 
metallic foil in an absolutely straight line, and exciting 
fluorescence when allowed to fall upon paper saturated with 
various chemicals, such as platinocyanide of barium or 
tungstate of calcium. Herr Lenard, of Hungary, examined 
these rays in 1864, and conducted numerous experiments. 
By placing the ordinary photographic plate and sensitive 
paper behind various substances, such as aluminum, wood, 
quartz, etc., he was able to obtain shadow images, or 
photographs, so called, showing the permeability of these 
substances to these rays. 
On applying an ordinary magnet to these rays, it was RONTGEN RAYS AND THE PIIOTO-FLUOROSCOPE. 
7 
found that they were deflected or attracted by the mag- 
net. Practically, then, we have come back to one of our 
first statements—namely, that the terms opaque, trans- 
lucent, and transparent are but relative; they are prac- 
tically interchangeable under certain conditions ; for quaitz, 
which is quite transparent to ordinary light, is absolutely 
opaque to these rays, and aluminum and cardboard of such 
a thickness as to be opaque to ordinary light are trans- 
parent or translucent to these rays. 
This brings me to the point of considering in a concise 
manner the new light of Rontgen, the new photography, the 
fiuoroscope, and their joint application in medicine and 
surgery. It is but a few weeks since the world was star- 
tled by the statement from Professor Rontgen that he was 
able to photograph through opaque objects. Naturally, this 
gave rise to considerable incredulity and fun at the expense 
of the learned professor, and even some of the shining 
lights in the scientific world were not loath to show their eru- 
dition by discounting the discovery, and ascribing the effects 
to the ultra-violet rays and the electric waves of Hertz. 
The discovery of these new rays, which bear the now famous 
name of Rontgen, was due, as is so often the case, entire- 
ly to accident. He was experimenting with a Crookes’s 
tube wrapped in an opaque material, and on his bench lay 
a piece of sensitive paper on which he found, after a power- 
ful current had passed through the tube, that a black line 
had been formed on the paper. Keenly alive to all extraor- 
dinary phenomena, the observant professor proceeded to 
investigate, with the result of the discovery of what is prac- 
tically something absolutely new, the value of which we 
can not at present entirely begin to appreciate. 
Now as to the difference between the cathodic and the 
“ X ” rays of Rontgen. The essential differences and similari- 
ties between the cathodic rays and “X” rays may well be 8 
RONTGEN RAYS AND THE PHOTO-FLUOROSCOPE. 
seen from his original communication. Nevertheless, a brief 
summarizing of these facts will bring them again before 
your notice. Rontgen light is not deflected by magnets, 
cathodic rays are; Rontgen rays are not absorbed or dif- 
fused so readily as cathodic rays. The Rontgen light will 
traverse several centimetres of wood and several millimetres 
of metal or glass, while cathodic rays fail to pass through 
any but thin films of glass, aluminum, etc. The Rontgen 
rays excite fluorescence and give shadow pictures at a dis- 
tance of many inches, and even feet, from the Crookes’s 
tube, while the cathodic rays are absorbed or diffused at a 
distance of fifty inches. The cathode rays proceed from 
the cathode itself, while, according to Rontgen, the “ X ” rays 
do not proceed from the cathode, but from that part of the 
glass where the cathode rays strike. The main points of 
similarity between the two are their powerful action on 
photographically sensitive films and their rectilinear propa- 
gation, as shown by the sharply defined shadows. 
How are these cathode rays formed ? 
The air is a bad conductor of electricity, and when the 
latter passes across an air space we observe a brilliant 
spark; but, as has been stated, by exhaustion of the air 
the character of the discharge is altered, a fact first discov- 
ered by Hittorf and worked out by Pliicker and Geissler, 
whose tubes are well known. Fantastic patterns are formed 
inside a vacuum, distinctly visible in various colors because 
of the peculiar nature of the glass or fluid which surrounds 
them. In 1879 Crookes replaced the cathode wire with a 
small flat or plane surface, and thus obtained a cylindrical 
beam of light which, proceeding in a straight line till it 
reached the opposite wall of the tube, behaved itself rather 
like a magnetic rod than like light, and possessed an elastici- 
ty of extraordinary character. The one end was closely con- 
nected to the negative electrode, the other, however, was free. RONTGEN RAYS AND THE PHOTO-FLUOROSCOPE. 
9 
It lias been well known for some time that this “ mag- 
netic rod,” or cathodic light, was extremely rich in ultra- 
violet rays, and that it possessed the power of exciting 
fluorescence and setting up chemical action. To explain 
these phenomena, Crookes assumed that this stream of 
light was caused by a continuous stream of molecules of 
gas of enormous rapidity, proceeding from the cathode, 
while in a Geissler tube, which contained more gas, this 
repulsion of the gas molecules from the negative pole was 
to some extent accompanied by continuous collisions of 
the gas molecules. This hypothesis received a decided 
blow by the discoveries of Hertz and Lenard. Hertz, 
stated that it must be possible to produce this phenomenon 
outside the vacuum tube, and that, being engendered in the 
tube, it must extend into tbe surrounding air. Lenard 
tested this experimentally, and found a substance which 
would allow the cathode rays to pass into the air. He ob- 
tained a Crookes’s tube, and at the end opposite the 
cathode, where these rays struck, he replaced the glass 
with a sheet of aluminum, which was of about the thick- 
ness of gold leaf, but was at the same time absolutely im- 
pervious to gases. By placing in the path of any rajs 
which might proceed from this aluminum window a piece 
of paper soaked with a fluorescent substance, Lenard 
proved conclusively that Hertz’s assumption was correct, 
and that Crookes’s explanation of the continuous stream of 
gas molecules was no longer tenable. Rontgen’s grand dis- 
covery followed all this. 
Now, having fairly touched upon the main principles 
and theories associated with these light rays, I shall call 
your attention to the screen, or fluoroscope. 
The accidental discovery of the phosphorescent screen 
by Rontgen and Lenard, and the latest improvement upon 
it by Thomas A. Edison, called by him the fluoroscope, are 10 
RONTGEN RAYS AND THE PIIOTO-FLUOROSCOPE. 
the outcome of the phosphorescence tubes. They are sim- 
ply tubes filled with certain phosphorescent powders and 
hermetically sealed. When the tubes are observed in a 
dark room (and of course before exposure to light), they 
are invisible; if, however, a piece of magnesium wire is 
burned close to the tubes, they will he found to shine in 
the dark and to emit various colored rays of faint light. 
To this curious effect is given the name of phosphorescence ; 
and the same result is also obtained when they are exposed 
to sunlight. The chemical substances which possess the 
property of developing light after exposure to light are 
called phosphori. There are many forms of these sub- 
stances known to us, prepared differently and hearing dif- 
ferent names. The phosphorescence of these various 
bodies, unlike that of the curious element phosphorus, is 
produced independently of any chemical change; if they 
are inclosed in sealed glass tubes and excluded from light, 
they retain the property of showing phosphorescence for 
many years, while the light emitted from phosphorus is 
due to the slow oxidation of this element. On placing it 
in water or in nitrogen, the light is no longer produced. 
This question of on what principle it is possible to explain 
the cause of the emission of light after exposing phos- 
phorus to the sun or any brilliant artificial light has given 
I’ise to several theories. 
The most rational one suggested is that the undulations 
of light convey their own vibratory motions to the phos- 
phori, just as one musical instrument may cause another to 
vibrate sympathetically with it, and phosphorescence is 
observed so long as the substance continues to vibrate in a 
dark room, and without a constant accession or supply of 
vibratory power the light becomes fainter and fainter until 
it is no longer capable of affecting the eye; the vibratory 
power, like any other mechanical motion, must come to an RONTGEN RAYS AND THE PHOTO-FLUOROSCOPE 
11 
end when cut off from its source of power, the sun or the 
burning magnesium, which originally set it in motion. 
This opinion is further confirmed when we take into ac- 
count the large number of substances which may become 
phosphorescent in a tolerably high degree. If this prop- 
erty was confined to a few bodies, the theory might not be 
so applicable ; but if it is agreed beforehand that any parti- 
cles may become luminous if they are capable of entering 
into that state of vibration which we suppose belongs to the 
sun and to artificial sources of light, then it can be under- 
stood why the great number of organic or inorganic sub- 
stances are all considered to enjoy in a limited degree the 
property of phosphorescence after exposure to the sun. 
Gmelin enumerated a large number of chemical bodies 
and common substances when he spoke of those things 
which became phosphorescent by irradiation. Also Edison 
examined 1,800 substances and found seventy-two that 
were fluoroscent. 
Now that we have traced the principle underlying the 
phosphorescent screen, or fluoroscope, a brief outline of this 
invention is in place. This screen is in its latest dress, as 
designed by Edison. It consists of a flaring box, curved 
at one end to fit over the forehead and eyes like a stereo- 
scope. The end of the box is closed by a pasteboard cover 
on the inside of which is spread a layer of tungstate of 
calcium, which, according to the inventor’s report, has been 
found to possess six times the fluorescent power under 
the influence of the “ X ” rays that barium platinocy- 
anide has. 
The practical applications of the screen are many. 
For simple illustration purposes, one has but to place the 
object to be observed in front of the screen and behind 
the vacuum tubes in a fluorescent state. The shadow is 
formed on the screen and can be observed at once. In Ground jf/ass to fix imaje on. 
Fig. 4. 
Screen orFluoroscope 
attached next to Plate 
Holder on hinje joints. 
Plate Holder. RONTGEN RAYS AND THE PHOTO-FLUOROSCOPE. 
13 
order to exclude all light from the screen, the curved part 
around the eyes is encircled by a lining of feathers. 
The photo-fluoroscope is an instrument which differs 
from all other fluoroscopes in the fact that it allows a direct 
shadow picture to he taken from the screen on the fluoro- 
scope, after it is focused through the screen, and the image 
is seen on the ground glass in the photographic focusing 
box. With this device it is possible first to see and judge 
of the object to be photographed, instead of making a pic- 
ture blindly—that is, without knowing what is in the nega- 
tive until it is developed. The Rontgen rays, when they 
pass through the screen, reach the ground glass by first 
passing through the object. When this is done, the sensi- 
tive plate in a holder is exposed next to the screen, and 
then allowed a certain time of exposure. 
The illustration shows the arrangement of the model. 
It consists of a photographic focus box, and ground glass, 
mounted on a movable table. To this box is attached on 
hinges a door, carrying a fluorescent screen, which closes 
directly over the sensitive plate. Just in front of the 
screen there is room for the object to be pictured, also a 
holder for placing the Crookes’s tube at any distance. The 
coil is on the same stand. 
The Rontgen method has not these advantages; by it 
one can never know what the result is to be until the nega- 
tive is developed. The time of exposing the plate is much 
shorter, and there are many other important considera- 
tions which make it particularly fit for the physician’s 
work. 
In many diseases of the chest, throat, and nose the 
diagnosis is often doubtful, especially in the bony and 
cartilaginous parts. There is no doubt in my mind that 
this process will aid us as much as it already has proved 
to be of great service in general surgery. 14 
RONTGEN rays and THE PIIOTO-FLUOROSCOPE. 
In the study and application of these rays and shadow 
photography in medicine and surgery the possibilities 
which were opened to us by this discovery are startling. 
No one can yet foreshadow the coming researches to be 
made. 
From what has been said and demonstrated thus far we 
can readily enough understand the lessons taught us by 
these various methods of taking Rontgen pictures and view- 
ing opaque objects with the screen and Crookes’s tube.