The world's oldest lightbulb turns 110 Saturday in Livermore, Calif., a tiny 4-watt night light that has burned its way into the Guinness World Records.
The bulb first lit up in 1901 when it was donated to the fire department -- before the Titanic sank and before San Francisco endured its disastrous quake.
On Saturday, the Livermore Firehouse, which has moved the bulb three or four times since 1901, is to celebrate the birthday with cakes, parades, speeches and a brass band.
What other lightbulb has its own profile on Facebook and is watched over by a webcam which offers round-the-clock proof of its continued activity?
"In our guestbook we have people from Germany, China, Japan, Russia, England, you name it," beams Lynn Owens, 67, the former division chief for the Livermore Fire Department who has looked after the bulb for 30 years.
As "spokesperson" for the Centennial Lightbulb, Owens has an answer to all questions but one.
"Why does she burn longer than all the others? That is the mystery that nobody knows," he says.
Lots of experts have tried to establish precisely why, but none of them came to a convincing conclusion.
"No one turns it on and off, maybe that's why it lasts so long," Owens guesses.
The bulb hangs well over five metres above the floor of the fire station, and the small switch at its base is out of reach.
The hand-blown bulb was made in the 1890s by Shelby Electrics Company in Ohio.
The owner of an energy company in Livermore gave it as a present to the local Fire Department, which was at the time still using kerosene lamps. So as not to not leave the station completely in the dark at night, the bulb was left burning 'round the clock.
"She was meant to be a little nightlight, it just gives the room a little warm glow," Owens notes.
With a carbon filament and just 4 watts, it tirelessly gives off a gentle, amber-yellow light. Night or day, nobody turns it off.
The bulb first caught the public eye in 1972, when a newspaper reporter looked into its longevity and suggested it should be in the Guinness World Records.
The true test came in 1976, with the move to a new firehouse. Wrapped in foam, with a siren-wailing police guard, it was rushed to a new site where it was carefully hung from the ceiling.
"It was off maybe at the most seven, eight minutes," Owens recalls.
A soft click on the old switch at the base, and it glowed on. It has not stopped since. Not even a power cut can get it, because it is plugged onto an emergency power appliance.
This bulb, which survived the 1906 San Francisco quake disaster 60 km distant from Livermore and numerous energy crises since, runs no risk of being replaced by a power-saving light bulb.
"Nobody will ever touch it again," Owens says.
"And if she burns out one day, the bulb will never leave Livermore."
Just in case, Ripley's Believe It Or Not Museum has already enquired about the possibility of taking it.
The bulb shows no signs of aging, not even a nervous flicker before its 110th birthday.
