An improved design of cup anemometer

A new design of three-cup anemometer is described possessing the following characteristics: (i) The minimum wind velocity in which the anemometer will function quite satisfactorily, about 0.2 m./sec. (40 ft./min.), is appreciably lower than usual with this type of anemometer, and compares favourably with other sensitive but more troublesome types of anemometer involving moving parts. (ii) The rate of rotation of the cups is related linearly with the wind velocity, and in consequence the indicated mean value of the velocity in a gusty wind is true, apart from the effects of inertia. (iii) The inertia of the moving parts is small so that the anemometer is very responsive to changes in wind velocity and overestimation in a gusty wind is negligibly small. (iv) The anemometer is portable and of relatively small dimensions.