Edison and the Electric Chair_ A Story of Light and Death - Mark Essig [22]
Figure 2: Compared to the older tree system (A), Edison's new feeder-and-main circuit design (B) required far less copper, one of the most expensive elements of an electric lighting system. The two cubes represent the amount of copper needed to light the same number of lamps using the tree system (C) and the feeder-and-main (D).
Even with the feeder-and-main circuit, the system required so much copper that the only way to make it pay was to build it in an area of high population density, so that many customers could be served with relatively few feet of feeders and mains. Lower Manhattan, the site of 52 Edison's chosen district, fit the bill perfectly. Edison sent a small army of canvassers into the fifty-one-square-block area to ask residents how many gas jets they had, how much gas they used at various times of the year, what their gas bills were, and whether they would be willing to try electric light. The canvassers found about 1,500 customers using 18,043 gas jets. Promised free wiring and prices comparable to those of gas, almost all of the customers agreed to try electricity.5
AS HE WORKED TOWARD the big dream of a Manhattan system, Edison was distracted by another project. Henry Villard, a major stockholder in the Edison Electric Light Company, also headed the Oregon Railway and Navigation Company. Impressed by Edison's New Year's demonstration, Villard decided that the incandescent light should be installed in the Oregon company's new steamship, the SS Columbia. Although reluctant to be distracted from his central station work, Edison decided that the Columbia offered a priceless opportunity to showcase his invention. The ship docked in Manhattan, and Edison's men set to work.
The Columbia's lighting system—the first commercial installation of incandescent lamps—was rather crude. Rough cotton dipped in paraffin served as insulation for the wires, which were tacked to the woodwork with iron staples; when wires crossed over metal, a sleeve of soft rubber was slipped over them. Edison's men developed the first lamp sockets, wooden devices with two metal strips inside that pressed against two strips at the base of the bulb. (In the laboratory, the lamp's lead-in wires had been wound around terminal screws, a method too complex for general use.) No one had yet conceived of the screw socket, so the bulbs sat rather loosely in their sockets. The Columbia project inspired the invention of the first "safety catch," or fuse, a strip of soft metal that melted and broke the circuit if the line overheated, thus preventing fires and allowing the insurance underwriters to sleep easier. The last items to be installed were the bulbs themselves. The filaments were so fragile that Edison's men wrapped them in cotton batting, placed them in baskets, and carried them by hand through the streets of New York, careful to avoid jostling by passersby.
If a passenger in a stateroom wanted the lamps turned on or off, he called a steward, who unlocked a box outside the room to turn the switch. Few passengers complained about this inconvenience, though, because electric lights were such an improvement over oil lamps, which quickly fouled the air of the small staterooms. The Columbia reached San Francisco on July 26,1880, and Californians flocked to see the spectacle of the new incandescent lamps. They were a bit disappointed, because about half the bulbs had expired en route, their brittle filaments fractured by the ship pitching in rough seas. A shipment