Solution:

• An instrument for measuring the speed of the wind, or of any current of gas.

• Anemometers measure wind speed by the amount of wind pressure against a surface, such as a cup or a propeller, or by using sonic pulses.

• A mechanical anemometer contains a wheel with cups or a propeller at the end of the spokes of the wheel. One of them contains a magnet. Each time the magnet passes a switch, it makes a recording. This can give an extremely accurate reading of the wind speed.

• There are several types of anemometers as well. A Sonic Anemometer, for example, uses disturbances and sound waves to calculate wind speed. It has no moving parts and relies on sonic pulse technology to measure both wind speed and direction.

• There are also Laser Doppler anemometers, plate and tube anemometers, wire anemometers, vane anemometers, and other designs.

• The Davis mechanical anemometer has sealed, stainless steel ball bearings that give it a long life under continuous use. It is rugged, but it is also accurate enough to measure the lightest breeze or change in wind speed.