Chicken Feathers

With most of us having to replace light-bulbs every few months, it’s amazing that the Centennial Light-Bulb at Fire Station No. 6 in Livermore, California, has been burning continuously ever since 1901.

The exact date the centennial bulb was turned on is unknown, although its birthday is usually celebrated on June 18. However, we do know that it has been alight 24 hours a day since then, shining a dim light over the fire engines. Apart from the few power outages it has faced in the last 113 years, the unbreakable light-bulb has only had two breaks – one in 1976, when it was moved from one fire station and installed in another, and one in 2013, when it was off for 9 3.4 hours. When the bulb was moved, almost 40 years ago, people were so cautious not to break it that they severed the cord, instead of unscrewing it, and transferred it with a full police and fire truck escort. The whole business lasted just 22 minutes, after which it was back to business as usual.
The impressive light-bulb is apparently an improved hand-blown incandescent lamp with carbon filament. Debora Katz, a physicist at the US Naval Academy in Annapolis, Md., has conducted extensive research on the centennial light-bulb and what makes it so special, using a vintage light bulb from Shelby Electric Co. that is a near replica of the Livermore lamp. “The Livermore light bulb differs from a contemporary incandescent bulb in two ways,” says Katz. “First its filament is about eight times thicker than a contemporary bulb. Second, the filament is a semiconductor, most likely made of carbon. When a conductor gets hotter, its ability to conduct electricity goes down. When the Shelby bulb gets hotter, it becomes a better conductor of electricity.”