How do you make mowing the lawn easier? Use a self-propelled mower.

Self-propelled mowers powered by gas will require you to keep an eye on the fuel and oil levels, the cleanliness of the air ...
The Why Files on MSN

They used sound to lift stones - was this the secret to the pyramids?

Ancient civilizations moved stones weighing hundreds of tons without cranes, pulleys, or modern machines. One theory? They used sound. And shockingly, science now shows acoustic levitation is real — ...