April 18, 2006 > TechKnow Talk
by Todd Griffin
I read there is a light bulb in Livermore that has been burning for 100 years. That can't be true, can it?
Yes, it is true. Well, it's essentially true, anyway. There is a bulb in a Livermore fire station that was originally donated to the city in 1901. Though this may seem an odd gift for a city, a light bulb was a valuable and rare commodity at that time; it was reportedly only the second one in town. The bulb was allegedly left on around the clock, so firemen arriving on emergency call at night would have an easier time finding their equipment.
Anecdotal evidence does suggest the bulb has been burning pretty much continuously since then, though it was turned off at least twice to be moved to new fire stations, most recently in 1976, when it was installed in its current location at 4550 East Ave. One must also presume there have been some power outages along the way, though the bulb is now wired into the building's emergency generator system, so it will take more than a blackout to extinguish its soft glow.
The humble, approximately 4-watt bulb was manufactured by the Shelby Electric Company, which was bought out by General Electric (GE) in 1914. The glass is hand blown. Engineers from GE and Lawrence Livermore National Labs have examined the bulb and authenticated its age. It is entered in both the Guinness Book of World Records and Ripley's Believe-It-or-Not as the oldest working light bulb. Since the 100-year celebration in 2001, the Livermore luminary has received tremendous media attention from newspapers, magazines, radio, and the major television networks. It is probably the most celebrated light bulb ever. A few other bulbs are known to have burned 50 years or more, but no others have approached the century mark.
Light bulb technology has changed little in 100 years. A thin filament is mounted in a thin glass bulb. The filament is heated to a very high temperature by passing an electric current through it. This causes the filament to emit light. In a future TechKnow Talk column, the physics of light generation will be discussed in illuminating detail, but we all know that heating a piece of metal can cause it to glow. Oxygen must be removed from the bulb to keep the filament from burning. Modern bulbs replace the air with an inert gas such as argon; early bulbs simply pumped out the air, leaving a vacuum.
The Livermore bulb probably used a carbon filament in a simple vacuum, as opposed to the modern design of a tungsten filament in argon, but it is otherwise similar in construction and materials to its modern equivalent. Why has it burned so long? No one knows for sure, but its low wattage and relatively thick filament have been cited as possible explanations. A careful dissection of the bulb could possibly shed some light on the question but, should it burn out, Livermore officials are not inclined to offer it for autopsy. In addition to the engineers who would analyze it, Ripley's museum has expressed an interest in exhibiting the bulb after it burns out. However, it is likely to remain on display in Livermore.
If the technology existed to produce a 100-year light bulb way back then, why don't modern bulbs last that long? The easy answer is to blame corporate greed and intentional obsolescence. The TechKnow Guy has an aversion to lawsuits, so will not speculate on that possibility. Keep in mind that this is a very dim bulb, a mere 4 watts. Most of us would be frustrated trying to read or light our homes from such a bulb, even though it might last a very long time. Modern bulbs generate a lot more light, and are also very inexpensive. No one will be impressed nowadays if you bequeath a light bulb to the city.
You may stop by the fire station during normal business hours and see the centennial light for yourself. It hangs unprotected about 15 feet above the firehouse floor. It also has its own enlightening web site, complete with "Bulbcam," so, should you feel the urge, you can watch the bulb 24x7. (www.centennialbulb.org).
How does a cactus survive in the desert heat for months and months without water?
Cacti belong to a family of plants called succulents. These amazing plants have evolved the ability to hold water in their leaves. Many cacti have taken this a step further by eliminating leaves entirely, in favor of a barrel- or column-shaped body. The exterior surface of the cactus acts as a leaf, converting sunlight into energy, while the interior is used as a water reservoir. After a rain, a cactus swells as it pulls water from an extensive, typically shallow root system into its body. As it gradually utilizes this water during dry periods, it shrinks and shrivels.
There exist an incredible variety of cacti. Not all live in the desert, though most do. Some even thrive high in the Andes, and rely on a winter blanket of snow to insulate them from the freezing temperatures. The reservoir method of water storage is very effective for drought tolerance, but renders cacti vulnerable to freezing.
Experts at surviving heat and drought, cacti use many techniques in addition to water storage. Many cacti sprout under an existing bush or against a rock, which offers shade for the young plant, until it has developed a root system capable of drawing in sufficient water to survive the intensity of the full sun. Most also produce sharp spines to repel thirsty animals from ripping them open to get at the water within. Some have adapted by developing a very dense thicket of spines or even "hair" to provide shade from the harsh desert sun.
Most cacti do well in cultivation, where they may get less sun and a little more water. If you are cultivating cacti at home, they are hardy survivors, requiring little care. You are more likely to kill a cactus by giving it too much attention than too little. The most common mistake is over-watering. There is no surer way to kill a cactus than by keeping its roots moist for an extended period of time. But treated properly, some adult specimens will reward you once or more each year with spectacular blooms.