Inventor Thomas Edison on October 21, 1879, began testing another type of filament for his electric light bulb.

The bulb gave light for 40 hours, marking Edison's first successful experiment with the electric light bulb, after thousands of failures in laboratory tests in Menlo Park, New Jersey.

The key to success was the use of a hair-thin carbon filament that glowed but did not melt from the heat generated by the electricity.

He declared to the lab workers: "If I could make it glow for 40 hours, I can make it glow for 100 hours."

On the basis of this lamp, Edison began the construction of the first successful lighting system, which would later supply power to 85 houses that his company had equipped with electrical circuits and light bulbs in New York.