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Working scientists took almost eighty years to "subdivide" electric light. Dozens of experimenters in Germany, England, France, Russia, and the United States worked on the development of an incandescent bulb in the decades after Sir Humphry Davy momentarily made a platinum filament glow at the Royal Institution in 1802, but they encountered seemingly insurmountable problems with the filaments they fashioned out of carbon, a platinum-iridium alloy, or asbestos, which they enclosed in vacuums or sometimes surrounded with nitrogen. Carbon, in all the experiments, quickly destroyed itself. Platinum, which resisted oxidation, tended to fuse when heated to incandescence, and it was expensive. Several experimenters managed to make a short-lived light from platinum in an evacuated bulb, the most lasting being William Grove's, which in 1840 illuminated an English theater for the length of a performance, though the light was dim and costly.

By the 1870s, all the problems scientists had encountered with incandescence throughout the century persisted, and the field was crowded with those who were still trying to adequately evacuate bulbs and craft enduring filaments. Among them were Hiram Maxim, Moses Farmer, William Sawyer, and Albon Man in the United States and St. George Lane-Fox and Joseph Swan in England. Swan had been attempting to make a filament lamp for thirty years, and the transactions of the December 1878 meeting of the Newcastle Chemical Society note that he "described an experiment he had recently performed on the production of light, by passing a current of electricity through a slender rod of carbon enclosed in an exhausted globe.... The rod became heated to such an intense degree as to cause it to glow with great splendour." Still, Swan's light was only momentary, and the glass bulb quickly became coated with soot.

Thomas Edison joined the fray in the late summer of 1878. "It was all before me," he was to later say. "I saw the thing had not gone so far but that I had a chance. I saw that what had been done had never been made practically useful. The intense light had not been subdivided so that it could be brought into private houses." Edison knew he not only had to find a durable material and an ideal shape for the filament, but he also had to produce an adequate insulating material and figure out how to quickly, efficiently, and completely evacuate the air from a glass bulb. He had to create an effective delivery system for electricity—which meant developing workable switches and wiring—and an efficient dynamo. The dynamo was a particular challenge (earlier electric devices, such as telegraphs and telephones, could run on batteries), and he found the solution to this problem during a trip to engineer William Wallace's factory in Connecticut, where Wallace manufactured both arc lamps and dynamos. There Edison encountered Wallace's "telemachon," a dynamo powerful enough to illuminate eight arc lamps simultaneously. The machine utterly inspired him. A New York Sun reporter who'd accompanied Edison on the trip noted that Edison "ran from the instrument to the lights and from the lights back to the instrument. He sprawled over a table with the SIMPLICITY OF A CHILD, and made all kinds of calculations. He estimated the power of the instrument and of the lights, the probable loss of power in transmission, the amount of coal the instrument would save in a day, a week, a month, a year, and the result of such saving on manufacturing." Edison himself remarked, "Now that I have a machine (Wallace's) to make the electricity, I can experiment as much as I please."

The challenges Edison faced were not only technical. Everything concerning the system needed to be cost-effective, practical enough for general use, and familiar enough to old forms to be easily adopted by the public, which meant being cleaner, more efficient, and more economical than the dominant late-nineteenth-century type of urban indoor lighting: