Although there were many experiments in the decades before, Thomas Alva Edison's incandescent light of 1879 was the first successful carbon filament incandescent lamp. His device passed an electric current through thin filaments of carbonized threads tightly sealed in a glass bulb from which all air had been removed by a vacuum pump. Edison increased the voltage steadily until incandescence (white heat) reached a stable and bright glow. He was able to keep the filaments glowing for 40 hours. Modern lamps for the home have a life up to 1,000 hours, and commercial lamps have a longer life.