The Edison system of send | ing four messages at the same time over | the same wire has been in use for twenty live or twenty-six years—since 1874 or 1875. These three great inventions place Edison on the pinnacle of inventive fame. One alone would have entitled hi m to permam nt recognition. HUNDREDS OF OTHER CONCEPTIONS. The three I have mentioned are the principal output of the Edison biain; but then, it must bercmeralertd there are hundreds of other conceptions which are almost on a par witli these. The reason why men of inventive mind seldom turn out more than one great invention is that one conception absorbs so rnueh time. They devote a large poition of their lives to perlectiug this one favourite idea, to the detriment of their other mental productions. Inventing something is not merely the evolution of an idea, it is working it ! out in its most perfect detail, which is the major part of the task. The very .fact of its being a great idea stems to preclude the evolution of anything else on a like scale, and usually the one idea inventor gives his life’s time up to. his great thought. | Edison has produced so much because i he is a rapid worker. To use a modern i phrase, he is a “ rusher ” in the truest 1 sense of the word. Once an idea enters his head nothing stops nor stays him in ! either demonstrating that that idea is a j success or pioving it to be n failure. His i mind is wonderfully practical, and he | wastes no time in getting down to busi

ness alter ne lias once started on the solution ol a problem. 1 If what Edison is working on proves to j be a failure he does not hesitate to acknowledge it at once. Ho is too great a man to think of hiding the fact that he has not succeeded in any line. His candour in these tilings is ono of Edison's greatest charms. To illustrate this: Not long ago I spoke to him about a fluorescent screen which he had given rne in 1896. 1 thought it one of the best screens I had ever used in connec tion with the X.-rays. 