XII. On the constants of the cup anemometer

Abstract

In a previous paper the author detailed experiments made by attaching anemometers to a whirling machine, and the conclusions to which they led. He was however doubtful of the accuracy of the method, and proposed one depending on the action of natural wind. He has tried this, and he thinks successfully. Two instruments of the Kew type, differing only in friction, were established 22 feet asunder on the roof of the house and 16 feet above it : the number of turns made by each, and the time, were recorded by a chronograph, and from these, v and v ', the velocity in miles per hour of the centres of the cups was known.