Anemometer is blowing on the back of the cup on the opposite end of the cross. Since a hollow hemisphere has a drag coefficient of .38 on the spherical side and 1.42 on the hollow side, more force is generated on the cup that is presenting its hollow side to the wind. Because of this asymmetrical force, torque is generated on the axis of the anemometer, causing it to spin. Theoretically, the speed of rotation of the anemometer should be proportional to the wind speed, because the force produced on an object is proportional to the speed of the fluid flowing
Alcoholic spirits measure used in Scotland and Northern Ireland. The landlord can chose one or the other but not both. Thimble measures are also used in 175ml and 250ml volumes for measuring wine. Although government stamped for the correct volume, the thimble measure does rely on the user measuring the wine out manually into the thimble. Alcoholic spirits measure Alcoholic spirits measures are instruments designed to measure exact amounts or shots of alcoholic spirits. The most common products used today to measure spirits are the thimble measure and the non-drip measure, often referred to as an optic. The terms "Optic", "Optic Pearl", "OpticJade"