II. On the determination of the constants of the cup anemometer by experiments with a whirling machine

Abstract

In his description of the cup anemometer (Transactions Royal Irish Academy, Vol. XXII), Dr. Robinson inferred from experiments on a very limited scale with Robins’ whirling machine, that the ultimate ratio of the wind’s velocity to that of the centre of the cups =3. Some recent experiments by M. Dohrandt show that this number is too great; but as some of the details appeared objectionable, and as they did not include all the necessary data for determining the constants, the author was desirous of repeating them. He was enabled to do this by a liberal grant from the Royal Society, and the results are given in this paper. After describing the apparatus and the locality in which it was established, he proceeds to explain the conditions of an anemometer’s action. Considering only two opposite cups, and supposing them in motion, the pressure on the concave surface is as that surface and the square of the resultant of the wind’s velocity V and v , that of the anemometer, and as a , the pressure of an unit V on the cup normal to the arm.