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 THOMAS A. EDISON 169 became interested was that relating to the electric light. It was in the year 1878, as Mr. Edison himself tells ns, that he saw in the laboratory of Professor Barker, at Philadelphia, the first arc lamp and soon after another plant which was be- ing taken around the country with a circus and which consisted of ten or fifteen lamps burning together in a series. Mr. Edi- son at once realized that the Ught was too bright and needed to be subdivided* He desired to obtain smidl lights which could be distributed among people's houses like gas lights, and in order to carry out this scheme organized the Edison Electric Light Company. The next step was to make each light independent of every other. This could not be done by having them bum in a series, hence they must bum in a multi- ple arc. Soon there dawned in his mind the idea of the incan- descent lamp as opposed to the arc light. To make the new incandescent lamp a success, it was neces- sary for Mr. Edison to find a filament. He spent thirteen months of unwearied experimentation with different metals, trying first carbon points and then platinum wire. Any one but Mr. Edison would have given up in despair, but he per- severed until at last success crowned his efforts. While plati- num wire gave a good light when electricity was passed through it, the wire would melt when the current became too strong. It was therefore necessary to find some substance which would become luminous without melting when charged with electricity. Some of the greatest scientists of England had investigated this subject and come to the conclusion that the subdivision of electric light was a problem that could not be solved. After experimenting with various metals Mr. Edison came to the conclusion that metals would not do. One day, when seated in his laboratory, he accidently took up a little bit of lamp black mixed with tar, which was being used for another purpose in his laboratory. He rolled this until he obtained a thin thread, resembling a piece of wire. Suddenly he began to wonder whether this thread, being carbon, of course, might not have the strength to withstand the electric current He began at once to experiment and rolled out fine threads preparatory to placing them in the lamps. With the