Windmills

mills driven by a current of air. They are used usually to grind grain, pump water, saw wood, and to perform other useful work. Aside from the fact that the Crusaders found windmills in use among the Saracens and brought back a knowledge of their use to Europe, authorities know little about their origin.

Small windmills are common in Germany and Holland. They are seen less frequently in France. They have disappeared almost entirely from England, their place being taken in the latter country by water and steam mills. In Europe the sail wheel is composed of two large beams crossing each other at right angles. Each of the four arms carries a framework on which a large cloth sail is stretched. In time of high wind or storm these sails are furled or rolled up. This wheel, as it may be called, faces the wind squarely. The sails are set on a slant, so that the wind in forcing its way past them pushes them aside, causing the wheel to rotate and turn an axle by means of which power is transferred to the millstones or other mechanism designed to do work.

A small windmill is to be seen near every German village. It stands, that is to say, it is balanced, on a wooden pivot. When the wind changes, the peasant proprietor clatters down a hanging stairway to the ground, taking care not to lose his wooden shoes, and, seizing a long wooden sweep, turns the entire mill around until the sails look squarely into the wind again. When the wind stops altogether the miller joins his wife in the field.

The Dutch windmill, so useful in pumping water out of the sunken areas, is constructed on a somewhat different plan. The top of the mill, to which the axle and the sails are attached, consists of a movable cap or turret. When the wind changes the proprietor puts his shoulder against the lower end of a sail beam and walks around on a sort of platform, pushing the sails before him until they face the desired direction. The people of Holland depend on the windmill to grind grain, saw wood, clean flax, grind paper pulp, and drain land. The Scandinavian windmill follows the Dutch type. Settlers have introduced both types throughout the North American states and provinces.

The farm windmill in common use in America is erected on slender trestle work of wood or iron. The entire face of the sail-wheel is occupied by light slats, so that the same amount of surface is presented to the wind with a comparatively small diameter. A tail constructed after the fashion of a weather vane keeps the wheel fronting the wind. The slats composing the wheel are set usually on pivots in such a way that a tornado turns them edge to the wind and saves the tower from being overthrown. It is estimated that there are half a million farm windmills, used chiefly for pumping water, in the United States alone. According to the last United States census there are sixty-eight manufactories of windmills. The number of mills made is not given, but their annual value is over $4,000,000.

One of the largest windmills in the world stands near Seal Rocks, San Francisco, California. It is used to pump water for the irrigation of Golden Gate Park. It is of the Dutch type. The round tower is 120 feet high and 50 feet in diameter. The four giant arms describe a circle 164 feet in diameter.

See Steam; Waterpower