electrician), calm as can be, lightly tapped the switch and it came on again."

The bulb has been the subject of dozens of news stories, magazines, books and television shows. It's featured in the Guinness Book of World Records and Ripley's Believe It or Not.

Dubbed the Centennial Bulb, it is a wonder among engineers and advocates of energy-efficient lightbulbs.

It's featured in a soon-to-be-released documentary, "The Lightbulb Conspiracy," about the planned obsolescence of lightbulbs.

Double-decked tour buses often stop by the fire station for viewing. The guest book shows visitors from China, Germany, Fresno and beyond.

Despite its worldwide fame, the bulb has humble beginnings. It was created in the late 1800s by the Shelby Electric Co. in Shelby, Ohio, according to retired Sandia technician Steve Bunn, who's devoted his retirement tostudying the bulb.

A French inventor named Adolphe Chaillet held the patent, and the bulb's secret probably died when he did.

Others have tried to decipher the mystery, however. Scientists - of which there are thousands around Livermore and its labs - have studied it for decades. Some, like David Tse, an electrical engineering professor at UC Berkeley, are skeptical.

"It's not possible. It's a prank," he said curtly, slamming down the phone.

Henry Slonsky, an electrical engineering student at San Francisco State, was more open-minded.

"It's highly unlikely, but it's possible if the bulb has a really strong vacuum," he said. "And back then they did make everything way over the top."

The bulb made its way from Shelby to Livermore via Dennis Bernal, owner of the local power company. After he sold