Finding your way

You can truly appreciate how far we've come in technology when you realize that sailors once measured speed by throwing something overboard and seeing how long the ship took to pass it.

That's the first thing you learn at the "Art & Evolution of Navigation" exhibit at the Museum of American Heritage in Palo Alto. Interesting. I may try it on the freeway.

Then there's the ever-popular “navigation by echo,” illustrated by a wooden ear trumpet you listened to in the fog while letting loose a foghorn. “Elapsed time between the blast and the echo gave the approximate distance from the reflection point,” says the exhibit.

It’s a fun little exhibit, especially educational for today’s whippersnappers who think the world revolves around those newfangled Google maps, which allow you to see the roof of your favorite McDonald's in Russia. Throw them a cross-staff and see if they can find the latitude of Honolulu using only a fake North Star on the wall.

There’s plenty of more modern stuff, too, including an aircraft magnetic compass, radio-based direction finders and info about how the Mars Rover finds its way around.

Should I give you the address of the museum, or do you want to find it yourself? Awright, awright: it’s at 351 Homer Ave. Open hours are 11 a.m. to 4 p.m. Friday through Sunday.

Pictured above: A revolution counter that counts the number of ship propeller revolutions, allowing you to estimate the distance the ship has traveled in a given time. Below: An old globe in the exhibit. Photos by Ron Evans.