In Edison Gets the Bright Light Right, Wired‘s Randy Alfred writes that, on October 21st, 1879,
Thomas Edison crowns 14 months of testing with an incandescent electric light bulb that lasts 13+ hours. Sir Humphrey Davy had produced incandescent electric light in 1808 by passing battery current through a platinum wire. But the voltaic pile was expensive and could be messy.”
….Soon, the [Menlo Park] lab got a carbon-filament bulb to last 40 hours. It had cost $40,000 (about $850,000 in today’s money) and taken 1,200 experiments, but was ready at last for a public debut.
On New Year’s Eve, 3,000 people visited the lab in Menlo Park to witness 40 electric light bulbs glowing merrily. Edison switched them on and off at will, dazzling and delighting his guests. These bulbs used carbonized cardboard.
