It was an October day 142 years ago, exactly in 1879, when Thomas Edison , the American inventor, lit the first incandescent light bulb , managing to keep one lit for about 13 hours.
In reality, before him an English chemist, Joseph Swan, had patented an incandescent light bulb, but with a carbon thread inside which, when burning, blackened the bulb of the lamp, making it dim and with a minimum lifespan.
Edison tested, one after the other, dozens and dozens of substances to replace carbon, including platinum, cotton and, it is said, even the red hairs of one of his collaborators' beards. It was a charred cotton thread, one of those used for sewing, that made him achieve the goal of obtaining a bright light bulb that lasts almost 2000 hours.
When Edison filed the patent for the lamp, Swan sued him and won. Eventually the two put together a company, the Edison & Swan United Light Company which, from 1882 onwards produced an average of 100 thousand light bulbs a year.
