It took 55 years before the telephone, invented in 1820, was put to use in society.
Sound travels over 14 times faster through steel than through air. If you need to signal someone quickly standing on a metal bridge, bang on a steel pipe!
The Great Pyramid of Cheops in Egypt, built about 2600 BC, was constructed with enough stone to make a brick wall that could go around the world 20 inches high.
In comparison, the largest modern building, the Pentagon, in Washington DC would only make a brick wall that went around the world two inches high.
If everyone in the world took a daily bath, our entire supply of fresh water would be get dirty in a single day.
The number of bacteria in a quart of soil from your backyard garden is 30 times greater than the population of the world.
When high sped trains past each other they must slow down or they will break their windows. The passing trains produce a low-pressure area between them that can actually pull the glass out of the frames.
A hydroplane can go much faster than a normal boat because it lifts the hull out of the water. It uses supports that act like underwater wings to give it lift. It is really just flying through water.
You can surf on only one or two inches of water. Jump on a wooden disc and you can ride 20 feet or more in the shallow water along the beach.
Manhole covers, the lids that cover sewers, are always round. Why? The round cover rests on a lip that is smaller than the cover so it can't drop through the opening. A square or rectangular cover, no matter how it was made, could fall through.
The fear of spiders is called arachnophobia. Some other phobias are hydrophobia (fear of water), triskaidekaphobia (fear of the number 13), ecclesiaphobia (fear of churches), pogonophobia (fear of beards), ergophobia (fear of work).
