Gravity Catapult

I have long been enamored of catapults. Invented around 400 B.C., they were used until nearly A.D. 1300. So for 1,700 years, catapults were arguably the largest, most expensive, and most powerful machines on the planet. Today, people build catapults for fun: Scout troops, historical reenactors, fathers and daughters, beer-stoked... Read more »

Electromagnetic Aluminum Levitator

About 13 years ago I learned of some military research into a satellite- and missile-defense device that would propel projectiles using Lenz’s law, which governs the direction of electrical current induced by a changing magnetic field. I decided to make a little gadget based on the same principle for my... Read more »