batteries never included

Oh yes, certainly, please click.

The Brooklyn Bridge.The C-47 airplane -- still flying over Himalayas and Andes and deep into jungles and tundra, and will continue to do so indefinitely while pilots stay reasonably sober and awake. The C-47 (a great favorite for smuggling drugs by air) has outlasted most of the first humans who flew it. They're not walking anymore. The C-47 is still flying.

All the voyages of human beings to the surface of the Moon.

Skyscrapers, well past the era of the Empire State Building and the Chrysler Building, well past the era of the Eiffel Tower.

The great ocean liners and naval and merchant vessels from the era of steam, and the submarines of both World Wars and the first nuclear submarines. All the world's railroads well past steam and into the Diesel and Electric era. And the great train stations, and the tunnels through the mountains for the railroads.

Relativity. Maxwell's Equations. The Periodic Table of the Chemical Elements. The atomic bomb.

All computed on a slide rule.

They never need batteries. They don't use batteries or electricity.

If the power goes out -- you can still compute. Perfect for being stranded on an island, and needing to compute so you can build a boat and navigate across the ocean to get home again safely. Perfect for your three-hour final examination.

How much precision do you need, anyway? In the physical universe, there aren't many questions that really need more than 6 digits of precision. A cheap student slide rule gives you 3 or 4.

Pay another $100 and you can get 5, maybe 6. But of course in the Great Age of Slide Rules, they made beautiful and amazing slide rules that cost $200, $300, $400 ... precision and dozens of special little extra tricks. My brother kept his in the refrigerator so the wood wouldn't warp in hot, humid weather.

They're extinct now.

Oh, want to use one again? Or learn how to use one for the first time in your life? Try this one.