Hot-air balloons Up, up, and away! If you love the idea of flying but you’ve nowhere in particular to go, a hot-air balloon could be just […]

Heat engines In our age of fuel cells and electric cars, steam locomotives (and even gasoline-powered cars) might seem like horribly old technology. But take a […]

Fuel cells Acentury or so ago, the number of cars on Earth numbered in the thousands. Today, there are something like a billion cars—roughly one for […]

Elevators   Hit the top button on the elevator and prepare yourself for a long ride: in just a few days you’ll be waving back from […]