Ship's Ventimeter

In original cardboard case in excellent condition with full instructions for use as well as how to interpret the wind strength measured. Designed for marine and meteorological use to measure wind speeds from o to 82 mph or force 0 (calm) to Hurricane Force 12! Whilst for sale as a collector's item, it appears to function correctly but cannot guarantee its accuracy, although the last one of these we sold went back to sea and we were told subsequently its readings aligned accurately with today's high tec equipment! Described on the packaging "durable, rust proof and buoyant"! We would estimate it dates from the mid 20th century. 7.5" (20 cm)