Chapter 12 A WORLD-HUNT FOR FILAMENT MATERIAL

IN writing about the old experimenting days at Menlo Park, Mr. F. R. Upton says: "Edison's day is twenty-four hours long, for he has always worked whenever there was anything to do, whether day or night, and carried a force of night workers, so that his experiments could go on continually. If he wanted material, he always made it a principle to hav