Edison and the Electric Chair_ A Story of Light and Death - Mark Essig [16]
When he first started work on the lamp, Edison abandoned carbon because of its tendency to burn, and because all earlier inventors had used thick carbon rods of low resistance. In the fall of 1879, however, he realized that he could make carbon just as thin as platinum wire. With his new, powerful vacuum, the carbon would not burn—no oxygen, no oxidation. After experimenting with different types of carbon burners, Edison and Batchelor took a piece of cotton thread, .0013 of an inch in diameter, and carbonized it in an oven. The filament—as the slender burners were now called—was attached to platinum lead-in wires and sealed inside an evacuated glass bulb. The lab notebook entry tells the tale: "on from 1:30 AM till 3 pm[:] 13 1/2 hours and was then raised to 3 gas jets for one hour then cracked glass & busted." It was an understated entry for a historic event. Edison and his men had finally created a practical incandescent lamp—one that would burn for hours and use very little energy.26
"It is an immense success," Edison told a friend. "Say nothing." Although it went against his nature, he remained silent because he wanted to be absolutely sure of success before the press learned of it. Dissatisfied with the carbon thread, Edison and his men tested hundreds of different sources of carbon. Finally, at Bachelor's urging, they tried a horseshoe-shaped piece of cardboard boiled in sugar and alcohol and then carbonized. It worked even better than carbon thread. "I think the Almighty made carbon especially for the electric light," Edison told a reporter.
Now Edison was ready to exhibit his light.27
He invited the public to Menlo Park for New Year's Eve, 1879, and before nightfall the roads to the town were clogged with carriages, wagons, and pedestrians, and railroad companies ordered special trains to carry the crush. Thousands of spectators thronged the streets until past midnight. When Edison appeared, attired in a rough suit of work clothes, the crowd surged toward him. Some shouted questions, ranging from "How'd you get the red-hot hairpin into that bottle?" to more informed queries about the horsepower required to power each bulb. Edison had become an expert at working a crowd, playing the role of the modest genius, explaining complex science in simple terms.28
The Edison incandescent lamp as it appeared in 1880.
The system was powered by three long-legged Mary-Ann dynamos and controlled by a telegraph key in the machine shop. The visitors never tired of pressing the key, turning the lights off and on. When one of Edison's men plunged a lamp into a jar of water, the crowd was astonished to see that the water did not quench the flame. But the lights in open air were astonishing enough. Two lamps glowed softly at the entrance to the library, eight more atop wooden poles along the roadway, and a string of thirty lit up the laboratory building.
To modern eyes, it would have seemed a rather modest display. But those assembled were among the first people in the world to see the marvelous glow of incandescent light. No flame, no flicker, no soot, no fumes—just pure, steady light.29
CHAPTER 4
Electricity and Life
EDISON'S ELECTRIC LIGHT inventions marked another triumph in the great tradition of electrical innovation that included Volta's battery, Faraday's researches in electromagnetism, Morse's telegraph, and the first powerful electrical generators built in the 1870s. In the shadows of this march of progress, however, a very different electrical tradition