Thomas Edison demonstrated his first incandescent light bulb on this date in 1879. While he didn't invent it, he did own the company that employed the inventors. After 14 months of testing, 1,200 experiments, and $40,000, he was finally ready for his first public demonstration. He hung strings of lights inside his lab in Menlo Park, New Jersey, and switched them on and off repeatedly, to the awe and delight of his 3,000 spectators. He said, "We will make electricity so cheap that only the rich will burn candles."