A toy gyroscope spins like a top. In fact, this toy is often called a gyrotop. The chief parts of the gyrotop are a wheel which is weighted around the rim and a rod, or axle, that goes through the center of the wheel. In spinning a gyrotop, a string is first wrapped around the axle. Then the string is pulled suddenly as the end of the axle is rested on something solid. Once a gyrotop starts spinning it does not change its position until it runs down. Its axle keeps on pointing in the same direction. It can remain in amazing positions as it spins. The whirling of the heavy wheel keeps it from falling.
Not all gyroscopes are toys. Some are used in boats as compasses. Some are used to keep boats and airplanes on a straight course. A gyroscope used in this way is called a gyropilot. One nickname for a gyropilot is "metal Mike." In fighting at sea during a war gyroscopes are used to guide torpedoes. On some ships enormous gyroscopes are used to help keep the ships on an even keel so that passengers will not be seasick.
Only toy gyroscopes are set to spinning by the pulling of a string. As a rule other gyroscopes are set in motion and kept spinning with electricity.