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October 21, 2006

Happy Lightbulb Day!

webcam image of the centennial lightbulb

There are no parades scheduled, but today, October 21st, is a date worthy of commemoration. On this date in 1879 Thomas Edison figured out the secret to the electric light bulb. Edison had spent months trying to find a workable filament material...one that would conduct electricity, that would glow brightly when electricity was passed through it, but that wouldn't quickly burn up or melt due to the high temperatures produced. Edison started out by trying platinum wire, and eventually tested scores of different materials without finding fit the bill.

At about 1:30 in the morning on this date, Edison tried a bit of carbonized cotton thread. He turned on the power and his light bulb glowed brightly...and continued to glow until 3 o'clock the next afternoon. This was a huge breakthrough -- within a year Edison had a bulb that could last more than 1,200 hours. (Typical modern incandescent light bulbs burn out a bit quicker than that, but they glow much brighter).

OK, 1,200 hours is impressive, but to be really impressed by lightbulb longevity, get yourself to the fire station at Livermore, California. Hanging from the ceiling in the fire engine garage, there's a lightbulb that was made in 1901. A lightbulb that's still glowing more than a century later! The bulb has been turned off a few times in the past 105 years, due to power failures and a brief period 30 years when the fire department moved to a new building, but it's been on every second since (they have it hooked up to a backup power supply to guard against future power outages).

There's a website about the Livermore lightbulb, and a live webcam so you can reassure yourself that the bulb is still glowing, at www.centennialbulb.org.

Posted by Chris Spurgeon at October 21, 2006 07:55 AM