The Invention Of The Incandescent Lamp - 2

The Invention Of The Incandescent Lamp - 2

Thus the new era had been ushered in, but it was based altogether on the consumption of
some material --carbon--in a lamp open to the air. Every lamp the world had ever known
did this, in one way or another. Edison himself began at that point, and his note-books
show that he made various experiments with this type of lamp at a very early stage.
Indeed, his experiments had led him so far as to anticipate in 1875 what are now known
as "flaming arcs," the exceedingly bright and generally orange or rose-colored lights
which have been introduced within the last few years, and are now so frequently seen in
streets and public places. While the arcs with plain carbons are bluish-white, those with
carbons containing calcium fluoride have a notable golden glow.
He was convinced, however, that the greatest field of lighting lay in the illumination of
houses and other comparatively enclosed areas, to replace the ordinary gas light, rather
than in the illumination of streets and other outdoor places by lights of great volume and
brilliancy. Dismissing from his mind quickly the commercial impossibility of using arc
lights for general indoor illumination, he arrived at the conclusion that an electric lamp
giving light by incandescence was the solution of the problem.
Edison was familiar with the numerous but impracticable and commercially unsuccessful
efforts that had been previously made by other inventors and investigators to produce
electric light by incandescence, and at the time that he began his experiments, in 1877,
almost the whole scientific world had pronounced such an idea as impossible of
fulfilment. The leading electricians, physicists, and experts of the period had been
studying the subject for more than a quarter of a century, and with but one known
exception had proven mathematically and by close reasoning that the "Subdivision of the
Electric Light," as it was then termed, was practically beyond attainment. Opinions of
this nature have ever been but a stimulus to Edison when he has given deep thought to a
subject, and has become impressed with strong convictions of possibility, and in this
particular case he was satisfied that the subdivision of the electric light--or, more
correctly, the subdivision of the electric current--was not only possible but entirely
practicable.
It will have been perceived from the foregoing chapters that from the time of boyhood,
when he first began to rub against the world, his commercial instincts were alert and
predominated in almost all of the enterprises that he set in motion. This characteristic trait
had grown stronger as he matured, having received, as it did, fresh impetus and strength
from his one lapse in the case of his first patented invention, the vote-recorder. The
lesson he then learned was to devote his inventive faculties only to things for which there
was a real, genuine demand, and that would subserve the actual necessities of humanity;
and it was probably a fortunate circumstance that this lesson was learned at the outset of
his career as an inventor. He has never assumed to be a philosopher or "pure scientist."
In order that the reader may grasp an adequate idea of the magnitude and importance of
Edison's invention of the incandescent lamp, it will be necessary to review briefly the
"state of the art" at the time he began his experiments on that line. After the invention of
the voltaic battery, early in the last century, experiments were made which determined
that heat could be produced by the passage of the electric current through wires of
platinum and other metals, and through pieces of carbon, as noted al- ready, and it was, of
course, also observed that if sufficient current were passed through these conductors they
could be brought from the lower stage of redness up to the brilliant white heat of
incandescence. As early as 1845 the results of these experiments were taken advantage of
when Starr, a talented American who died at the early age of twenty-five, suggested, in
his English patent of that year, two forms of small incandescent electric lamps, one
having a burner made from platinum foil placed under a glass cover without excluding
the air; and the other composed of a thin plate or pencil of carbon enclosed in a
Torricellian vacuum. These suggestions of young Starr were followed by many other
experimenters, whose improvements consisted principally in devices to increase the
compactness and portability of the lamp, in the sealing of the lamp chamber to prevent
the admission of air, and in means for renewing the carbon burner when it had been
consumed. Thus Roberts, in 1852, proposed to cement the neck of the glass globe into a
metallic cup, and to provide it with a tube or stop-cock for exhaustion by means of a
hand-pump. Lodyguine, Konn, Kosloff, and Khotinsky, between 1872 and 1877,
proposed various ingenious devices for perfecting the joint between the metal base and
the glass globe, and also provided their lamps with several short carbon pencils, which
were automatically brought into circuit successively as the pencils were consumed. In
1876 or 1877, Bouliguine proposed the employment of a long carbon pencil, a short
section only of which was in circuit at any one time and formed the burner, the lamp
being provided with a mechanism for automatically pushing other sections of the pencil
into position between the contacts to renew the burner. Sawyer and Man proposed, in
1878, to make the bottom plate of glass instead of metal, and provided ingenious
arrangements for charging the lamp chamber with an atmosphere of pure nitrogen gas
which does not support combustion.