Edison, His Life and Inventions [101]
impossible, so called, had been attained; subdivision of the electric- light current was made practicable; the goal had been reached; and one of the greatest inventions of the century was completed. Up to this time Edison had spent over $40,000 in his electric-light experiments, but the results far more than justified the expenditure, for with this lamp he made the discovery that the FILAMENT of carbon, under the conditions of high vacuum, was commercially stable and would stand high temperatures without the disintegration and oxidation that took place in all previous attempts that he knew of for making an incandescent burner out of carbon. Besides, this lamp possessed the characteristics of high resistance and small radiating surface, permitting economy in the outlay for conductors, and requiring only a small current for each unit of light--conditions that were absolutely necessary of fulfilment in order to accomplish commercially the subdivision of the electric-light current.
This slender, fragile, tenuous thread of brittle carbon, glowing steadily and continuously with a soft light agreeable to the eyes, was the tiny key that opened the door to a world revolutionized in its interior illumination. It was a triumphant vindication of Edison's reasoning powers, his clear perceptions, his insight into possibilities, and his inventive faculty, all of which had already been productive of so many startling, practical, and epoch-making inventions. And now he had stepped over the threshold of a new art which has since become so world-wide in its application as to be an integral part of modern human experience.[9]
[9] The following extract from Walker on Patents (4th edition) will probably be of interest to the reader:
"Sec. 31a. A meritorious exception, to the rule of the last section, is involved in the adjudicated validity of the Edison incandescent-light patent. The carbon filament, which constitutes the only new part of the combination of the second claim of that patent, differs from the earlier carbon burners of Sawyer and Man, only in having a diameter of one-sixty-fourth of an inch or less, whereas the burners of Sawyer and Man had a diameter of one-thirty-second of an inch or more. But that reduction of one-half in diameter increased the resistance of the burner FOURFOLD, and reduced its radiating surface TWOFOLD, and thus increased eightfold, its ratio of resistance to radiating surface. That eightfold increase of proportion enabled the resistance of the conductor of electricity from the generator to the burner to be increased eightfold, without any increase of percentage of loss of energy in that conductor, or decrease of percentage of development of heat in the burner; and thus enabled the area of the cross-section of that conductor to be reduced eightfold, and thus to be made with one-eighth of the amount of copper or other metal, which would be required if the reduction of diameter of the burner from one-thirty-second to one-sixty- fourth of an inch had not been made. And that great reduction in the size and cost of conductors, involved also a great difference in the composition of the electric energy employed in the system; that difference consisting in generating the necessary amount of electrical energy with comparatively high electromotive force, and comparatively low current, instead of contrariwise. For this reason, the use of carbon filaments, one-sixty-fourth of an inch in diameter or less, instead of carbon burners one-thirty-second of an inch in diameter or more, not only worked an enormous economy in conductors, but also necessitated a great change in generators, and did both according to a philosophy, which Edison was the first to know, and which is stated in this paragraph in its simplest form and aspect, and which lies at the foundation of the incandescent electric lighting of the world."
No sooner had the truth of this new principle been established than the work to establish it firmly and commercially was carried on more assiduously than ever. The next immediate step was a further investigation
This slender, fragile, tenuous thread of brittle carbon, glowing steadily and continuously with a soft light agreeable to the eyes, was the tiny key that opened the door to a world revolutionized in its interior illumination. It was a triumphant vindication of Edison's reasoning powers, his clear perceptions, his insight into possibilities, and his inventive faculty, all of which had already been productive of so many startling, practical, and epoch-making inventions. And now he had stepped over the threshold of a new art which has since become so world-wide in its application as to be an integral part of modern human experience.[9]
[9] The following extract from Walker on Patents (4th edition) will probably be of interest to the reader:
"Sec. 31a. A meritorious exception, to the rule of the last section, is involved in the adjudicated validity of the Edison incandescent-light patent. The carbon filament, which constitutes the only new part of the combination of the second claim of that patent, differs from the earlier carbon burners of Sawyer and Man, only in having a diameter of one-sixty-fourth of an inch or less, whereas the burners of Sawyer and Man had a diameter of one-thirty-second of an inch or more. But that reduction of one-half in diameter increased the resistance of the burner FOURFOLD, and reduced its radiating surface TWOFOLD, and thus increased eightfold, its ratio of resistance to radiating surface. That eightfold increase of proportion enabled the resistance of the conductor of electricity from the generator to the burner to be increased eightfold, without any increase of percentage of loss of energy in that conductor, or decrease of percentage of development of heat in the burner; and thus enabled the area of the cross-section of that conductor to be reduced eightfold, and thus to be made with one-eighth of the amount of copper or other metal, which would be required if the reduction of diameter of the burner from one-thirty-second to one-sixty- fourth of an inch had not been made. And that great reduction in the size and cost of conductors, involved also a great difference in the composition of the electric energy employed in the system; that difference consisting in generating the necessary amount of electrical energy with comparatively high electromotive force, and comparatively low current, instead of contrariwise. For this reason, the use of carbon filaments, one-sixty-fourth of an inch in diameter or less, instead of carbon burners one-thirty-second of an inch in diameter or more, not only worked an enormous economy in conductors, but also necessitated a great change in generators, and did both according to a philosophy, which Edison was the first to know, and which is stated in this paragraph in its simplest form and aspect, and which lies at the foundation of the incandescent electric lighting of the world."
No sooner had the truth of this new principle been established than the work to establish it firmly and commercially was carried on more assiduously than ever. The next immediate step was a further investigation