For air in a submarine to remain usable, three things must happen: The oxygen must be replenished as it is consumed, the carbon dioxide must be removed from the air, and the moisture in human breath must also be removed.
Built before the invention of electric pumps, fountains in Rome were powered through an ingenious system of gravity, cisterns, and aqueducts. Learn more about fountains in Rome in this HowStuffWorks podcast.
The clear, thin sap of Maple trees must be boiled down to create maple syrup -- it takes about 30 to 40 gallons of sap to create one gallon of syrup. Check out this HowStuffWorks podcast to learn more about Maple syrup.
As sunlight passes through the atmosphere, particles in the air scatter blue light more efficiently than any other color in the light spectrum, creating a blue sky. Learn more about the sky and light in this Brainstuff podcast.
Although most people are frightened by radiation, the truth is we are irradiated every day, both from cosmic rays in the sky, and radioactive elements in the ground. Learn more about radiation in this HowStuffWorks podcast.
The flash of a camera is bright enough to cause a reflection off the human retina -- the red we see in these photos comes from the blood vessels in the eye. Learn more about red eyes and cameras in this HowStuffWorks podcast.
Although the speed of computers is growing exponentially, the human brain may handle roughly ten quadrillion instructions per second. Learn more about the world's fastest computer in this HowStuffWorks podcast.
A company named Nanosolar is shaking up the alternative energy industry by offering solar technology at the lowest prices in history -- even cheaper than energy derived from coal. Learn more about Nanosolar in this HowStuffWorks podcast.