PHOTOGRAPHY
Photography is one of the many triumphs of the human mind over time and
space. Thousands of miles are between you and the wonderful Taj Mahal.
You may never be able to go to it. But as the mountain would not go to
Mohammed and Mohammed therefore went to the mountain, so photography
brings the Taj Mahal to you. The chief struggle for civilization is
with these two abstract antagonists--time and space. In this struggle
the achievements of photography are such as to win it a place among the
world's great inventions and discoveries.
Here, again, we borrow words from the Greeks. _Photography_ comes from
the Greek noun _phos_ meaning "light" and the Greek verb _graphein_
signifying "to write," already referred to several times in this
volume. Photography is therefore the science and the art of writing or
reproducing objects by means of light. The science of photography
depends upon the action of light on certain chemicals, usually
compounds of silver. These chemicals are spread upon a delicately
sensitized metallic plate, which is exposed to light. The action of
light fixes the object desired upon this plate, from which copies of
the picture are made on paper of suitable kind.
Like most of the great discoveries and inventions, photography is not
old. It had its beginning in 1777, when the Swedish chemist Scheele
began to inquire scientifically into the reason and effect of the
darkening of silver chloride by the rays of the sun. The first picture
ever made by the use of light on a sensitive surface was made in 1791
by Thomas Wedgewood, an Englishman. The principle of the photographer's
camera was discovered in 1569 by Della Porta, of Naples. To Nicephore
Niepce, a Frenchman, belongs the honor of producing the first camera
picture. This was in 1827 after thirteen years of experimenting. He
called his process "heliography," _helios_ being the Greek word for
_sun_. His process consisted of coating a piece of plated silver or
glass with asphaltum or bitumen, and exposing the plate in the camera
for a time varying in length from four to six hours. The light acted on
the asphaltum in such a way as to leave the image on the plate.
The predecessor of the modern photograph was the daguerreotype. It was
named for its inventor, Louis Daguerre, a French scene-painter, who was
born in 1789. In 1829 he formed a partnership with Niepce, and together
they labored to advance the art of photography. The discovery of the
daguerreotyping process was announced in January, 1839. The process of
Daguerre consisted in "exposing a metal plate covered with iodide of
silver for a suitable time in a photographic camera, the plate being
afterwards transferred to a dark room, and exposed to the vapor of
mercury, which develops the latent image, it being afterwards fixed.
Although this process has become almost obsolete, it was really the
first which was of any practical value, and experts all agree that no
other known process reproduces some subjects--for example, the human
face--with such fidelity and beauty."
A little while before the daguerreotyping process was announced, Fox
Talbot, a British investigator, discovered a method of making pictures
by means of the action of light on chemically prepared paper instead
of metal, as in the case of Daguerre. Talbot originated the terms
_negative_ and _positive_ which are still used in photography.
Daguerre in France and Talbot in Great Britain had independently
achieved success in producing pictures, but neither had discovered a
way to make photographs permanent. In the course of time the pictures
faded. In 1839 Sir John Herschel of England found a chemical process
for making photographs permanent, by removing the cause for their
fading. The first sunlight photograph of a human face was that of Miss
Dorothy Catherine Draper, made by her brother, Prof. John William
Draper, of the University of the City of New York, early in 1840.
Various chemical discoveries for improving photographs have been made
by different persons from time to time, until the art of photography
has now reached a high state of development. An important improvement
is in the lessening of the time of exposure to light necessary for
producing a photograph. Formerly hours were required, but under
improved conditions only the shortest instant of time is requisite.
In 1906 a photographic paper for producing prints in color from an
ordinary negative was placed on the market. This paper is coated with
three layers of pigmented gelatin, colored respectively red, yellow,
and blue. After being exposed to the daylight in the usual way, the
paper is placed in hot water, where the image is developed. The grays
and blacks of the negative are translated into the colors they
represent in the object.
The brothers Lumiere of Paris have found a method of producing a
photograph on a sensitive plate which, viewed as a transparency, shows
the object in its original colors. No prints can be taken from this
plate, and the picture cannot be viewed by reflected light, but the
colors are true and brilliant.
The cinematograph is an instrument by which about fifteen photographs
per second can be received on a film, each representing the
photographed group at a different instant from the others. The
advantages of this mode of photographing and of throwing pictures on a
screen over the older methods are obvious. By controlling the rate at
which the pictures are represented on the screen, movements too rapid
to be analyzed by the eye may be made slow enough to permit
observation; and, similarly, movements too slow for comprehension or
rapid observation may often be quickened. The busy life of a city
street, the progress of races or other competitions, many scenes in
nature, and even the growth of a plant from seed to maturity, may be
shown by means of a "moving picture."
Photography is a noble servant of mind and soul. It brings to us
likenesses of eminent persons and objects of nature and art which
perhaps we should never be able to see otherwise. It has been used in
measuring the velocity of bullets and in showing the true positions of
animals in motion. Photography has created the "new astronomy."
Immediately after its discovery, photography was applied to the science
of the stars, and it has been ever since of incalculable service in
this field of inquiry. Photographs of the moon were made as early as
1840, and much that is known to-day of the sun has been revealed by
photography. So sensitive is the modern photographic plate to the
influence of light, that photography has discovered and located stars
which are invisible through a strong telescope. Astronomers are now
engaged in making a photographic chart of the sky.