A very big lightbulb: The stick welder provides enough juice to heat the tungsten to nearly 5,000 Photo by Mike Walker

Dept.: Gray Matter
Element.: Tungsten
Project: Making a lightbulb
Time: 30 minutes
Cost: Roughly $50
Dabbler | | | | | MasterThomas Edison famously spent months trying to make a lightbulb work. He tested one material after another in an evacuated bell jar before he finally got a carbon filament to burn long enough to sell it with a straight face. When I had a free afternoon recently, I thought I'd see if I could do it too.

Edison's first mistake was living before tungsten wire was available. Tungsten is way better than carbon as a filament material, and now you can find it in any metal-supply shop. It lasts longer, is less brittle, and glows with a cleaner, whiter light. His second mistake, repeated in classroom physics demonstrations to this day, was using a vacuum to get the air out of the bulb. Clearing out the air is important because at yellow to white heat (3,500