Fire Sprinkler, String Trimmer, Electric ToothbrushThe fire sprinklers we know today grew from systems developed all the way back in the 1850s. When a fire broke out, workers pumped water through these pipes, where it then rained down, extinguishing the flare up. Their popularity in factories was immediate, but fire sprinklers for the home took a while to catch on. Fueled by their safety record, fire sprinklers now protect more lives and property than ever. Next, the string trimmer had its humble beginnings in the mind of Texas businessman George Ballas. While driving through a car wash in 1972, he noticed that the fast-spinning brushes that made his car so clean it did no damage to the paint. This got him thinking of a grass trimmer that would cut grass near his trees without damaging the bark. His design was a shearing success and the first models hit the market within two years. Finally, in 1939, the first practical electric toothbrush was introduced in Switzerland, just one year after nylon bristles started appearing in the brush. By the time electric toothbrushes made it to the U.S. market in the '60s, they had become unplugged, getting their power from rechargeable batteries. The popularity of the electric toothbrush was inconsistent until the 1990s, when improved brush head movements and conclusive studies showed a huge benefit from their use.
