Science and technology in the United States finish. For example, the British engineer Joseph Swan built an incandescent electric lamp in 1860, almost 20 years before Edison. But Edison's light bulbs lasted much longer than Swan's, and they could be turned on and off individually, while Swan's bulbs could be used only in a system where several lights were turned on or off at the same time. Edison followed up his improvement of the light bulb with the development of electrical generating systems. Within 30 years, his inventions had introduced electric lighting into millions of homes. Another landmark application of scientific ideas to practical uses was the
Henry Woodward (inventor) fully effective and sufficiently promising; they sold their to Thomas Edison. Thomas Edison obtained an exclusive license to the Canadian patent. Thomas Edison developed his own design of incandescent lamp with a high resistance thin filament of carbon in a high vacuum contained in a tightly sealed glass bulb which had a sufficiently long service life to be commercially practical. The relationship of the Woodward/Evans work on the incandescent bulb to that of others, including Edison, on electric light is explained in the following passage of an article in a 1900 issue of "Electrical World and Engineer" as follows: "The