All About Inventions and Discoveries
The Romance of modern scientific and mechanical Achievements

274 All About Inventions designed by two industrious inventors, Bradley and Lovejoy, and was set to work. Excellent results were achieved, but the necessary apparatus suffered from the fatal disability of being too complicated for com- merce, the upshot being that the first effort to turn Cavendish’s discovery to commercial advantage came to an end in the summer of 1904. But the new industry had advanced to such a stage that it refused to be arrested by this initial failure. While Bradley and Lovejoy were striving to make their system a success, two other investigators had solved the problem. Professor Kristian Birke- land, of Christiania, in collaboration with a fellow- citizen, Mr. Samuel Eyde, a well-known engineer, produced an electric furnace in 1903, the distinctive feature of which was the large intense flame which had been previously laid down by Sir William Crookes as absolutely indispensable to success. For many years Professor Birkeland had devoted his attention to the study of the Aurora Borealis, and these re- searches had induced him to make several fascinating experiments with electric discharges. Ten years were devoted to this line of investiga- tion, and as a result of the knowledge he had accumu- lated so painstakingly, he was induced to probe more closely the peculiar action which a transverse mag- netic field exercises upon an alternating electric current passed between the tips of two conductors or electrodes. In the ordinary electric arc lamp, in which alternating current is employed, the luminous flame is but a fraction of an inch in length—the gap between the two points. But the Professor observed that by the aid of magnets, bearing upon the arc at