Books: Marvels of Modern Science
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Paul Severing >> Marvels of Modern Science
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These experiments proved that if stations were erected of sufficient
power transatlantic wireless could be successfully carried on. They
gave an impetus to the erection of such stations.
On December 21, 1902, from a station at Glace Bay, Nova Scotia, Marconi
sent the first message by wireless to England announcing success to
his colleagues.
The following January from Wellsfleet, Cape Cod, President Roosevelt
sent a congratulatory message to King Edward. The electric waves
conveying this message traveled 3,000 miles over the Atlantic following
round an arc of forty-five degrees of the earth on a great circle, and
were received telephonically, by the Marconi magnetic receiver at
Poldhu.
Most ships are provided with syntonic receivers which are tuned to
long distance transmitters, and are capable of receiving messages up
to distances of 3,000 miles or more. Wireless communication between
Europe and America is no longer a possibility but an accomplishment,
though as yet the system has not been put on a general business basis.
[Footnote: As we go to press a new record has been established in
wireless transmission. Marconi, in the Argentine Republic, near Buenos
Ayres, has received messages from the station at Clifden, County Galway,
Ireland, a distance of 5,600 miles. The best previous record was made
when the United States battleship _Tennessee_ in 1909 picked up a
message from San Francisco when 4,580 miles distant.]
CHAPTER III
RADIUM
Experiments of Becquerel--Work of the Curies--Discovery of
Radium--Enormous Energy--Various Uses.
Early in 1896 just a few months after Roentgen had startled the
scientific world by the announcement of the discovery of the X-rays,
Professor Henri Becquerel of the Natural History Museum in Paris
announced another discovery which, if not as mysterious, was more
puzzling and still continues a puzzle to a great degree to the present
time. Studying the action of the salts of a rare and very heavy mineral
called uranium Becquerel observed that their substances give off an
invisible radiation which, like the Roentgen rays, traverse metals and
other bodies opaque to light, as well as glass and other transparent
substances. Like most of the great discoveries it was the result of
accident. Becquerel had no idea of such radiations, had never thought
of their possibility.
In the early days of the Roentgen rays there were many facts which
suggested that phosphorescence had something to do with the production
of these rays It then occurred to several French physicists that X-rays
might be produced if phosphorescent substances were exposed to sunlight.
Becquerel began to experiment with a view to testing this supposition.
He placed uranium on a photographic plate which had first been wrapped
in black paper in order to screen it from the light. After this plate
had remained in the bright sunlight for several hours it was removed
from the paper covering and developed. A slight trace of photographic
action was found at those parts of the plate directly beneath the
uranium just as Becquerel had expected. From this it appeared evident
that rays of some kind were being produced that were capable of passing
through black paper. Since the X-rays were then the only ones known
to possess the power to penetrate opaque substances it seemed as though
the problem of producing X-rays by sunlight was solved. Then came the
fortunate accident. After several plates had been prepared for exposure
to sunlight a severe storm arose and the experiments had to be abandoned
for the time being. At the end of several days work was again resumed,
but the plates had been lying so long in the darkroom that they were
deemed almost valueless and it was thought that there would not be
much use in trying to use them. Becquerel was about to throw them away,
but on second consideration thinking that some action might have
possibly taken place in the dark, he resolved to try them. He developed
them and the result was that he obtained better pictures than ever
before. The exposure to sunlight which had been regarded as essential
to the success of the former experiments had really nothing at all to
do with the matter, the essential thing was the presence of uranium
and the photographic effects were not due to X-rays but to the rays
or emanations which Becquerel had thus discovered and which bear his
name.
There were many tedious and difficult steps to take before even our
present knowledge, incomplete as it is, could be reached. However,
Becquerel's fortunate accident of the plate developing was the beginning
of the long series of experiments which led to the discovery of radium
which already has revolutionized some of the most fundamental
conceptions of physics and chemistry.
It is remarkable that we owe the discovery of this wonderful element
to a woman, Mme. Sklodowska Curie, the wife of a French professor and
physicist. Mme. Curie began her work in 1897 with a systematic study
of several minerals containing uranium and thorium and soon discovered
the remarkable fact that there was some agent present more strongly
radio-active than the metal uranium itself. She set herself the task
of finding out this agent and in conjunction with her husband, Professor
Pierre Curie, made many tests and experiments. Finally in the ore of
pitchblende they found not only one but three substances highly
radio-active. Pitchblende or uraninite is an intensely black mineral
of a specific gravity of 9.5 and is found in commercial quantities in
Bohemia, Cornwall in England and some other localities. It contains
lead sulphide, lime silica, and other bodies.
To the radio-active substance which accompanied the bismuth extracted
from pitchblende the Curies gave the name _Polonium_. To that which
accompanied barium taken from the same ore they called _Radium_ and to
the substance which was found among the rare earths of the pitchblende
Debierne gave the name _Actinium_.
None of these elements have been isolated, that is to say, separated
in a pure state from the accompanying ore. Therefore, _pure radium_
is a misnomer, though we often hear the term used. [Footnote: Since
the above was written Madame Curie has announced to the Paris Academy
of Sciences that she has succeeded in obtaining pure radium. In
conjunction with Professor Debierne she treated a decegramme of bromide
of radium by electrolytic process, getting an amalgam from which was
extracted the metallic radium by distillation.] All that has been
obtained is some one of its simpler salts or compounds and until
recently even these had not been prepared in pure form. The commonest
form of the element, which in itself is very far from common, is what
is known to chemistry as chloride of radium which is a combination of
chlorin and radium. This is a grayish white powder, somewhat like
ordinary coarse table salt. To get enough to weigh a single grain
requires the treatment of 1,200 pounds of pitchblende.
The second form of radium is as a bromide. In this form it costs $5,000
a grain and could a pound be obtained its value would be
three-and-a-half million dollars.
Radium, as we understand it in any of its compounds, can communicate
its property of radio-activity to other bodies. Any material when
placed near radium becomes radio-active and retains such activity for
a considerable time after being removed. Even the human body takes on
this excited activity and this sometimes leads to annoyances as in
delicate experiments the results may be nullified by the element acting
upon the experimenter's person.
Despite the enormous amount of energy given off by radium it seems not
to change in itself, there is no appreciable loss in weight nor
apparently any microscopic or chemical change in the original body.
Professor Becquerel has stated that if a square centimeter of surface
was covered by chemically pure radium it would lose but one thousandth
of a milligram in weight in a million years' time.
Radium is a body which gives out energy continuously and spontaneously.
This liberation of energy is manifested in the different effects of
its radiation and emanation, and especially in the development of heat.
Now, according to the most fundamental principles of modern science,
the universe contains a certain definite provision of energy which can
appear under various forms, but which cannot be increased. According
to Sir Oliver Lodge every cubic millimeter of ether contains as much
energy as would be developed by a million horse power station working
continuously far forty thousand years. This assertion is probably based
on the fact that every corpuscle in the ether vibrates with the speed
of light or about 186,000 miles a second.
It was formerly believed that the atom was the smallest sub-division
in nature. Scientists held to the atomic theory for a long time, but
at last it has been exploded, and instead of the atom being primary
and indivisible we find it a very complex affair, a kind of miniature
solar system, the centre of a varied attraction of molecules, corpuscles
and electrons. Had we held to the atomic theory and denied smaller
sub-divisions of matter there would be no accounting for the emissions
of radium, for as science now believes these emissions are merely the
expulsion of millions of electrons.
Radium gives off three distinct types of rays named after the first
three letters of the Greek alphabet--Alpha, Beta, Gamma--besides a
gas emanation as does thorium which is a powerfully radio-active
substance. The Alpha rays constitute ninety-nine per cent, of all the
rays and consist of positively electrified particles. Under the
influence of magnetism they can be deflected. They have little
penetrative power and are readily absorbed in passing through a sheet
of paper or through a few inches of air.
The Beta rays consist of negatively charged particles or corpuscles
approximately one thousandth the size of those constituting the Alpha
rays. They resemble cathode rays produced by an electrical discharge
inside of a highly exhausted vacuum tube but work at a much higher
velocity; they can be readily deflected by a magnet, they discharge
electrified bodies, affect photographic plates, stimulate strongly
phosphorescent bodies and are of high penetrative power.
The radiations are a million times more powerful than those of uranium.
They have many curious properties.
If a photographic plate is placed in the vicinity of radium it is
almost instantly affected if no screen intercepts the rays; with a
screen the action is slower, but it still takes place even through
thick folds, therefore, radiographs can be taken and in this way it
is being utilized by surgery to view the anatomy, the internal organs,
and locate bullets and other foreign substances in the system.
A glass vessel containing radium spontaneously charges itself with
electricity. If the glass has a weak spot, a scratch say, an electric
spark is produced at that point and the vessel crumbles, just like a
Leyden jar when overcharged.
Radium liberates heat spontaneously and continuously. A solid salt of
radium develops such an amount of heat that to every single gram there
is an emission of one hundred calories per hour, in other words, radium
can melt its weight in ice in the time of one hour.
As a result of its emission of heat radium has always a temperature
higher by several degrees than its surroundings.
When a solution of a radium salt is placed in a closed vessel the
radio-activity in part leaves the solution and distributes itself
through the vessel, the sides of which become radio-active and luminous.
Radium acts upon the chemical constituents of glass, porcelain and
paper, giving them a violet tinge, changes white phosphorous into
yellow, oxygen into ozone and produces many other curious chemical
changes.
We have said that it can serve the surgeon in physical examinations
of the body after the manner of X-rays. It has not, however, been much
employed in this direction owing to its scarcity and prohibitive price.
It has given excellent results in the treatment of certain skin
diseases, in cancer, etc. However it can have very baneful effects on
animal organisms. It has produced paralysis and death in dogs, cats,
rabbits, rats, guinea-pigs and other animals, and undoubtedly it might
affect human beings in a similar way. Professor Curie said that a
single gram of chemically pure radium would be sufficient to destroy
the life of every man, woman and child in Paris providing they were
separately and properly exposed to its influence.
Radium destroys the germinative power of seeds and retards the growth
of certain forms of life, such as larvae, so that they do not pass
into the chrysalis and insect stages of development, but remain in the
state of larvae.
At a certain distance it causes the hair of mice to fall out, but on
the contrary at the same distance it increases the hair or fur on
rabbits.
It often produces severe burns on the hands and other portions of the
body too long exposed to its activity.
It can penetrate through gases, liquids and all ordinary solids, even
through many inches of the hardest steel. On a comparatively short
exposure it has been known to partially paralyze an electric charged
bar.
Heat nor cold do not affect its radioactivity in the least. It gives
off but little light, its luminosity being largely due to the
stimulation of the impurities in the radium by the powerful but
invisible radium rays.
Radium stimulates powerfully various mineral and chemical substances
near which it is placed. It is an infallible test of the genuineness
of the diamond. The genuine diamond phosphoresces strongly when brought
into juxtaposition, but the paste or imitation one glows not at all.
It is seen that the study of the properties of radium is of great
interest. This is true also of the two other elements found in the
ores of uranium and thorium, viz., polonium and actinium. Polonium,
so-called, in honor of the native land of Mme. Curie, is just as active
as radium when first extracted from the pitchblende but its energy
soon lessens and finally it becomes inert, hence there has been little
experimenting or investigation. The same may be said of actinium.
The process of obtaining radium from pitchblende is most tedious and
laborious and requires much patience. The residue of the pitchblende
from which uranium has been extracted by fusion with sodium carbonate
and solution in dilute sulphuric acid, contains the radium along with
other metals, and is boiled with concentrated sodium carbonate solution,
and the solution of the residue in hydrochloric acid precipitated with
sulphuric acid. The insoluble barium and radium sulphates, after being
converted into chlorides or bromides, are separated by repeated
fractional crystallization.
One kilogram of impure radium bromide is obtained from a ton of
pitchblende residue after processes continued for about three months
during which time, five tons of chemicals and fifty tons of rinsing
water are used.
As has been said the element has never been isolated or separated in
its metallic or pure state and most of the compounds are impure. Radium
banks have been established in London, Paris and New York.
Whenever radium is employed in surgery for an operation about fifty
milligrams are required at least and the banks let out the amount for
about $200 a day. If purchased the price for this amount would be
$4,000.
CHAPTER IV
MOVING PICTURES
Photographing Motion--Edison's Kinetoscope--Lumiere's
Cinematographe--Before the Camera--The Mission of the Moving
Picture.
Few can realize the extent of the field covered by moving pictures.
In the dual capacity of entertainment and instruction there is not a
rival in sight. As an instructor, science is daily widening the sphere
of the motion picture for the purpose of illustration. Films are rapidly
superseding text books in many branches. Every department capable of
photographic demonstration is being covered by moving pictures.
Negatives are now being made of the most intricate surgical operations
and these are teaching the students better than the witnessing of the
real operations, for at the critical moment of the operation the picture
machine can be stopped to let the student view over again the way it
is accomplished, whereas at the operating table the surgeon must go
on with his work to try to save life and cannot explain every step in
the process of the operation. There is no doubt that the moving picture
machine will perform a very important part in the future teaching of
surgery.
In the naturalist's domain of science it is already playing a very
important part. A device for micro-photography has now been perfected
in connection with motion machines whereby things are magnified to a
great degree. By this means the analysis of a substance can be better
illustrated than any way else. For instance a drop of water looks like
a veritable Zoo with terrible looking creatures wiggling and wriggling
through it, and makes one feel as if he never wanted to drink water
again.
The moving picture in its general phase is entertainment and instruction
rolled into one and as such it has superseded the theatre. It is
estimated that at the present time in America there are upwards of
20,000 moving picture shows patronized daily by almost ten million
people. It is doubtful if the theatre attendance at the best day of
the winter season reaches five millions.
The moving picture in importance is far beyond the puny functions of
comedy and tragedy. The grotesque farce of vaudeville and the tawdry
show which only appeals to sentiment at highest and often to the base
passions at lowest.
Despite prurient opposition it is making rapid headway. It is entering
very largely into the instructive and the entertaining departments of
the world's curriculum. Millions of dollars are annually expended in
the production of films. Companies of trained and practiced actors are
brought together to enact pantomimes which will concentrate within the
space of a few minutes the most entertaining and instructive incidents
of history and the leading happenings of the world.
At all great events, no matter where transpiring, the different moving
picture companies have trained men at the front ready with their cameras
to "catch" every incident, every movement even to the wink of an
eyelash, so that the "stay-at-homes" can see the _show_ as well, and
with a great deal more comfort than if they had traveled hundreds,
or even thousands, of miles to be present in _propria persona_.
How did moving pictures originate? What and when were the beginning?
It is popularly believed that animated pictures had their inception
with Edison who projected the biograph in 1887, having based it on
that wonderful and ingenious toy, the Zoetrope. Long before 1887,
however, several men of inventive faculties had turned their attention
to a means of giving apparent animation to pictures. The first that
met with any degree of success was Edward Muybridge, a photographer
of San Francisco. This was in 1878. A revolution had been brought about
in photography by the introduction of the instantaneous process. By
the use of sensitive films of gelatine bromide of silver emulsion the
time required for the action of ordinary daylight in producing a
photograph had been reduced to a very small fraction of a second.
Muybridge utilized these films for the photographic analysis of animal
motion. Beside a race-track he placed a battery of cameras, each camera
being provided with a spring shutter which was controlled by a thread
stretched across the track. A running horse broke each thread the
moment he passed in front of the camera and thus twenty or thirty
pictures of him were taken in close succession within one or two seconds
of time. From the negatives secured in this way a series of positives
were obtained in proper order on a strip of sensitized paper. The strip
when examined by means of the Zoetrope furnished a reproduction of the
horse's movements.
The Zoetrope was a toy familiar to children; it was sometimes called
the wheel of life. It was a contrivance consisting of a cylinder some
ten inches wide, open at the top, around the lower and interior rim
of which a series of related pictures were placed. The cylinder was
then rapidly rotated and the spectator looking through the vertical
narrow slits on its outer surface, could fancy that the pictures inside
were moving.
Muybridge devised an instrument which he called a Zoopraxiscope for
the optical projection of his zoetrope photographs. The succession of
positives was arranged in proper order upon a glass disk about 18
inches in diameter near its circumference. This disk was mounted
conveniently for rapid revolution so that each picture would pass in
front of the condenser of an optical lantern. The difficulties involved
in the preparation of the disk pictures and in the manipulation of the
zoopraxiscope prevented the instrument from attracting much attention.
However, artistically speaking, it was the forerunner of the numerous
"graphs" and "scopes" and moving picture machines of the present day.
It was in 1887 that Edison conceived an idea of associating with his
phonograph, which had then achieved a marked success, an instrument
which would reproduce to the eye the effect of motion by means of a
swift and graded succession of pictures, so that the reproduction of
articulate sounds as in the phonograph, would be accompanied by the
reproduction of the motion naturally associated with them.
The principle of the instrument was suggested to Edison by the zoetrope,
and of course, he well knew what Muybridge had accomplished in the
line of motion pictures of animals almost ten years previously. Edison,
however, did not employ a battery of cameras as Muybridge had done,
but devised a special form of camera in which a long strip of sensitized
film was moved rapidly behind a lens provided with a shutter, and so
arranged as to alternately admit and cut off the light from the moving
object. He adjusted the mechanism so that there were 46 exposures a
second, the film remaining stationary during the momentary time of
exposure, after which it was carried forward far enough to bring a new
surface into the proper position. The time of the shifting was about
one-tenth of that allowed for exposure, so that the actual time of
exposure was about the one-fiftieth of a second. The film moved,
reckoning shiftings and stoppages for exposures, at an average speed
of a little more than a foot per second, so that a length of film of
about fifty feet received between 700 and 800 impressions in a circuit
of 40 seconds.
Edison named his first instrument the kinetoscope. It came out in 1893.
It was hailed with delight at the time and for a short period was much
in demand, but soon new devices came into the field and the kinetoscope
was superseded by other machines bearing similar names with a like
signification.
A variety of cameras was invented. One consisted of a film-feeding
mechanism which moves the film step by step in the focus of a single
lens, the duration of exposure being from twenty to twenty-five times
as great as that necessary to move an unexposed portion of the film
into position. No shutter was employed. As time passed many other
improvements were made. An ingenious Frenchman named Lumiere, came
forward with his Cinematographe which for a few years gave good
satisfaction, producing very creditable results. Success, however, was
due more to the picture ribbons than to the mechanism employed to feed
them.
Of other moving pictures machines we have had the vitascope, vitagraph,
magniscope, mutoscope, panoramagraph, theatograph and scores of others
all derived from the two Greek roots _grapho_ I write and _scopeo_ I
view.
The vitascope is the principal name now in use for moving picture
machines. In all these instruments in order that the film projection
may be visible to an audience it is necessary to have a very intense
light. A source of such light is found in the electric focusing lamp.
At or near the focal point of the projecting lantern condenser the
film is made to travel across the field as in the kinetoscope. A water
cell in front of the condenser absorbs most of the heat and transmits
most of the light from the arc lamp, and the small picture thus highly
illuminated is protected from injury. A projecting lens of rather short
focus throws a large image of each picture on the screen, and the rapid
succession of these completes the illusion of life-like motion.
Hundreds of patents have been made on cameras, projecting lenses and
machines from the days of the kinetoscope to the present time when
clear-cut moving pictures portray life so closely and so well as almost
to deceive the eye. In fact in many cases the counterfeit is taken for
the reality and audiences as much aroused as if they were looking upon
a scene of actual life. We can well believe the story of the Irishman,
who on seeing the stage villain abduct the young lady, made a rush at
the canvas yelling out,--"Let me at the blackguard and I'll murder
him."
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