Swinging vane anemometer
Swing Vane Anemometer
Air Flow Meters & Anemometers | eBay
Model 480 Vaneometer™ Swing Vane Anemometer
Description: Furthermore, since the wind varies in direction and the axis has to follow its changes, a wind vane or some other contrivance to fulfill the same purpose must be employed. Weston added a tag to one cup, which causes the cupwheel speed to increase and decrease as the tag moves alternately with and against the wind. Its construction is simple yet rugged. The air flow past the cups in any horizontal direction turned the shaft at a rate that was roughly proportional to the wind speed.