The Invention Of The Incandescent Lamp - 5

The Invention Of The Incandescent Lamp - 5

Edison was inclined to concur in the prevailing opinion as to the easy destructibility of
carbon, but, without actually settling the point in his mind, he laid aside temporarily this
line of experiment and entered a new field. He had made previously some trials of
platinum wire as an incandescent burner for a lamp, but left it for a time in favor of
carbon. He now turned to the use of almost infusible metals-- such as boron, ruthenium,
chromium, etc.--as separators or tiny bridges between two carbon points, the current
acting so as to bring these separators to a high degree of incandescence, at which point
they would emit a brilliant light. He also placed some of these refractory metals directly
in the circuit, bringing them to incandescence, and used silicon in powdered form in glass
tubes placed in the electric circuit. His notes include the use of powdered silicon mixed
with lime or other very infusible non-conductors or semi- conductors. Edison's
conclusions on these substances were that, while in some respects they were within the
bounds of possibility for the subdivision of the electric current, they did not reach the
ideal that he had in mind for commercial results.
Edison's systematized attacks on the problem were two in number, the first of which we
have just related, which began in September, 1877, and continued until about January,
1878. Contemporaneously, he and his force of men were very busily engaged day and
night on other important enterprises and inventions. Among the latter, the phonograph
may be specially mentioned, as it was invented in the late fall of 1877. From that time
until July, 1878, his time and attention day and night were almost completely absorbed by
the excitement caused by the invention and exhibition of the machine. In July, feeling
entitled to a brief vacation after several years of continuous labor, Edison went with the
expedition to Wyoming to observe an eclipse of the sun, and incidentally to test his
tasimeter, a delicate instrument devised by him for measuring heat transmitted through
immense distances of space. His trip has been already described. He was absent about
two months. Coming home rested and refreshed, Mr. Edison says: "After my return from
the trip to observe the eclipse of the sun, I went with Professor Barker, Professor of
Physics in the University of Pennsylvania, and Doctor Chandler, Professor of Chemistry
in Columbia College, to see Mr. Wallace, a large manufacturer of brass in Ansonia,
Connecticut. Wallace at this time was experimenting on series arc lighting. Just at that
time I wanted to take up something new, and Professor Barker suggested that I go to
work and see if I could subdivide the electric light so it could be got in small units like
gas. This was not a new suggestion, because I had made a number of experiments on
electric lighting a year before this. They had been laid aside for the phonograph. I
determined to take up the search again and continue it. On my return home I started my
usual course of collecting every kind of data about gas; bought all the transactions of the
gas- engineering societies, etc., all the back volumes of gas journals, etc. Having obtained
all the data, and investigated gas-jet distribution in New York by actual observations, I
made up my mind that the problem of the subdivision of the electric current could be
solved and made commercial." About the end of August, 1878, he began his second
organized attack on the subdivision of the current, which was steadily maintained until he
achieved signal victory a year and two months later.