What is the light bulb that has been burning since 1901?

Livermore’s Centennial Light combines heavy early construction, low output, steady power, and very few switching cycles.

1. Its hand-blown glass and dense carbon filament came from an era of different lamp construction.
2. The bulb now emits roughly four watts, so it runs cooler and under less stress.
3. Keeping it on avoids repeated heating and cooling that can damage filaments.
4. A live webcam lets observers confirm that it continues to glow.