Anemometer
an instrument designed to measure the velocity of the wind. It was invented by Wolfins in 1709. The anemometer most commonly in use consists of four light metallic hemispheres, called (from Dr. Robinson, who first employed them) Robinson's cups, which are made to revolve like a vane or weather-cock, and are found to do so at the rate of exactly one-third the velocity of the wind. The result is then recorded in pencil marks by a self-registering apparatus.