196 THOMAS A. EDISON 



ments of carbon, although naturally quite fragile owing to 

 their length and small mass, had a smaller radiating surface 

 and higher resistance than we had dared hope. We had 

 virtually reached the position and condition where the carbons 

 were stable. In other words, the incandescent lamp as we 

 still know it to-day, in essentially all its particulars unchanged, 

 had been born. 



We began immediately to make vacuum pumps and to 

 produce these paper filament lamps on them. During that 

 November we made perhaps as many as 100 of such lamps, 

 and the same month saw us plunged deep in experiments and 

 inventions on dynamos, regulators, meters, circuits, etc., all 

 just as necessary to the success of the art as the Httle lamp 

 itself. Some of those paper filament lamps had a remarkably 

 long life. Each yielded from 12 to 16 candle power and they 

 were burned on chandeliers until they gave out. The average 

 life was about 300 hours. One of them lasted 940 hours and 

 another 1,350 hours, so that commercial success and a new 

 industry were already well in sight. 



But I was not quite satisfied as to paper, or even with the 

 more regular and homogeneous wood fibre filaments, and thus 

 came to take up bamboo. We happened to have a palm leaf 

 fan on one of the tables. I was then investigating everything 

 with a microscope, so I picked it up and found that it had a 

 rim on the outside, of bamboo, a very long strip cut from the 

 outer edge. We soon had that cut up into blanks and car- 

 bonized. On putting these filaments into the lamps we were 

 gratified to see that the lamps were several times better than 

 any we had succeeded in making before. I soon ascertained 

 why and started a man off for Japan on a bamboo hunt. Be- 

 fore I got through I had tested no fewer than 6,000 vegetable 

 growths, and had ransacked the world for the most suitable 

 bamboo. The use of bamboo was maintained for many years 

 until other processes dealing with such material as cellulose 

 had been perfected. We tried even at the earliest moment of 

 success a number of experiments and things afterwards taken 

 up again or followed through, as for example, burning the 

 paper filaments in a vacuum charged with inert gas; and a 



