Thomas A. Edison: Some of His Great Inventions
While numerous small inventions were thought of, made, and patented in an almost incredibly short space of time, you must not think that Edison never had any hindrances or difficulties. There were inventions on which he and his assistants labored for years, spending tens of thousands of dollars before reaching satisfactory results.
It would take too long to name all of Edison's inventions, and it would be impossible to describe them all. There are very few departments of electrical invention to which he has not contributed something. The electric railroad and the automobile have received a share of his thought. His telephone; the megaphone, which carries the sound of the voice great distances without the help of wires; the quadruplex telegraph; the tasimeter, which measures the heat of the stars; or the kinescope, -- any one of them would have made the inventor famous. But he is perhaps best known by the invention of the incandescent electric light and the phonograph.
Every American boy and girl has Edison's name closely associated with the brilliant little globes of light, which are seen by thousands along city streets, in churches, in theaters, in public halls, and even in private dwellings.
A traveler in far off Egypt asked an ignorant donkey boy if he had ever heard of the President of the United States. He had not. He next asked if he had ever heard of Edison. With a nod of intelligence, the boy pointed to the electric light before the door of the hotel for answer.
Edison once said that the electric light had cost him more time, anxiety, and expense than any other invention. It was, however, the invention, which made him independently rich.
The principle of the light is simple. When an electric current passes from a good conductor to a poor one it causes heat. That a bright light might be obtained by non-conducting substances heated in this way, had been known for many years, but no one before Edison was able to turn the knowledge to practical use.
Even Edison found.it extremely difficult to make an inexpensive, durable, and strong light. The greatest difficulty was to find a non-conducting filament strong enough to endure, and slight enough to be heated to a white glow with a moderate charge of electricity.
Those will never forget it, who were present at Menlo Park when the search for the filament was begun. Experiment after experiment failed, while the "wizard," growing only more wide awake and resolute, begged his associates, "Let us make one before we sleep.”
Expeditions were made to Japan, India, Africa, and South America in search of the best possible material for the filament.
Men were unwilling to believe that the incandescent electric light could be used extensively for illuminating purposes. But in the winter of 1880, a public exhibit of the new invention was given at Menlo Park. The streets and trees were brilliantly lighted, and the laboratory was aglow inside and out with the dazzling white lights. Special trains were run to Menlo Park. Hundreds of people went to see the novel spectacle and all who saw were convinced that the incandescent light was a success.
The phonograph, while not so familiar to us as the electric light, arouses our wonder even more. You have perhaps heard that sound is made by vibrations of air. You have shouted in a bare room and heard the echo of your words come back with startling distinctness. The wall received the vibrations and sent back other vibrations making similar but somewhat blurred sounds. This repetition of the vibrations to get a repetition of sound is the principle on which the phonograph is based.
Edison gives an interesting account of the dawning of the idea in his mind: He says: "I was singing to the mouthpiece of a telephone, when the vibrations of the voice sent the fine steel point into my finger. That set me to thinking. If I could record the actions of the point and send the point over the same surface afterward, I saw no reason why the thing would not talk.
I tried the experiment first on a strip of telegraph paper, and found that the point made an alphabet. I shouted the words ‘Halloo! Halloo!' into the mouthpiece, ran the paper back over the steel point, and heard a faint ‘Halloo! Halloo!' in return. I determined to make a machine that would work accurately, and gave my assistants instructions, telling them what I had discovered. "
Frances M. Perry, “The Story of Thomas A. Edison: Inventions.” In Four American Inventors: A Book for Young Americans, New York, Cincinnati, and Chicago: American Book Company, 1901, Pages 251-255.