Page:Encyclopædia Britannica, Ninth Edition, v. 24.djvu/637

Rh W I N W I N 599 the expedition to the Scheldt, and thought the charges brought against the duke of York, as commander- in-chief, required his retirement from office. At the same time he actively opposed the bill of Sir Samuel Romilly, his col league on most political questions, for reducing the number of offences visited with the punishment of death. In July 1809 he received a blow on the hip whilst rendering assistance at a fire, which he thought little of at the time; but a tumour subsequently formed on the spot and an operation became necessary. This brought on a fever, and Windham rapidly sank. He died on 4th June 1810, and was buried in the family vault at Felbrigg. Windham was tall and well-proportioned ; and the impressive- ness of his speeches was heightened by the excellence of his address. Exercise of all kinds had charms for him. He attended all the celebrated prize-fights of his day, and he more than once spoke in the House of Commons against the prevention of bull-baiting. Nor did he neglect the pleasures of literature and science. His speeches were published in three volumes in 1806, with a memoir by Thomas Amyot, his private secretary while he was in office in 1806, and his Diary was edited by Mrs Henry Baring in 1866. The passages in the latter work relative to Dr Johnson s declining days have been of considerable use to the later editors of Boswell. WINDMILL. The date when windmills were first erected is unknown ; but they were certainly used in Europe in the 12th century. Of late they have generally been replaced by steam engines in Great Britain ; but they are still extensively employed in Holland in draining the polders and grinding trass. In America they are largely used ; Wolff states that in some cities in the United States over 5000 windmills are manufactured annually. In spite of the competition of more powerful and tractable motors, windmills may often be used with success and economy, especially in new countries where fuel is scarce, and for Avork which can be done intermittently. The Indian Government recently made inquiries with a view to using windmills for irrigation, and a good deal of information will be found in a report by Colonel Brownlow in the Pro fessional Papers on Indian Engineering, vol. viii. A wind mill is not a very powerful motor, and in its employment its power is variable and intermittent. In good situations it will generally work for about eight hours out of the twenty-four on an average. Small windmills are useful on farms for working machines and pumping, in brickfields for pumping, and on ships for clearing out bilge water. They are employed for drainage purposes in Holland and Nor folk, and for mining purposes in some new countries. In America they are used to pump water at railway stations. Sir W. Thomson has proposed to utilize them in charging electric accumulators. As an auxiliary to a steam engine they are sometimes useful ; thus at Faversharn a 15-horse- power windmill raised in ten months 21,000,000 gallons of water from a depth of 109 feet, saving 100 tons of coal. European Windmills. In all the older windmills a shaft, called the wind shaft, carried four to six arms or whips on which long rectangular narrow sails were spread. The wind shaft was placed at an inclination of 10 or 15 with the horizontal, to enable the sails to clear the lower part of the mill. The whip carrying the sail was often 30 to 40 feet in length, so that the tips of the sails described a circle 60 to 80 feet in diameter. The sails were rectangu lar, 5 to 6 feet wide, and occupying five-sixths of the length of the whip. A triangrilar leading sail was sometimes added. Sometimes the sails consisted of a sail-cloth spread on a framework ; at other times narrow boards were used. The oldest mill was no doubt the post mill, the whole struc ture being carried on a post; to bring the sails to face the wind, the structure was turned round by a long lever. The post mill was succeeded by the toiver, smock, or frock mill, in which the mill itself consisted of a stationary tower, and the wind shaft and sails were carried in a revolving cap rotating on the top of the tower. Meikle introduced in 1750 an auxiliary windmill or fan, placed at right angles to the principal sails, for automatically turning the mill face to the wind. If the wind shifts, the small fan begins to revolve and, acting through gearing, rotates the cap of the mill. Mills are exposed to great danger if the sails are not reefed or furled in high winds, and the reefing serves also to prevent the speed of the mill becoming excessive. In 1807 Sir W. Cubitt introduced automatic reefing arrange ments. The sails were made of thin boards held up to the wind by a weight. As the strength of the wind increased, the boards were pressed back and exposed less surface. American Windmills. American windmills generally have the sails arranged in an annulus or disk. The sails consist of narrow boards or slats arranged radially, each board inclined at a constant angle of weather (see below) ; and the impulse of the wind on these inclined surfaces drives the mill. An American mill presents a larger sur face for a given length of sail, and consequently the con struction is lighter. To turn the mill face to the wind, a simple large rudder or fish-tail is used, projecting back wards in a plane at right angles to the plane of rotation of the sails. There are a great variety of mills in America, but those most commonly used are of two types. (1) In those which have side-vane governor wheels the action equivalent to reefing the sails is effected by turning the whole wheel formed by the sails oblique to the wind, so as to diminish the wind s action. A side vane projects in the plane of rotation of the wheel, and the pressure of the wind on this tends to turn the wheel edgeways to the wind. This turning force is counterbalanced by a weight. Hence for moderate winds the wheel is held up face to the wind ; for stronger winds it is turned obliquely. (2) In centrifugal governor mills the slats forming the wheel are connected together in sets of six or eight, each set being fixed on a bar at about the middle of its length. By rotating this bar, the boards or slats are brought end on to the wind, the action being analogous to shutting an umbrella. The boards are held up to the wind by a weight, and are also connected to a centrifugal governor. If the speed of the governor increases, the balls fly out and lift the weight; at the same time the sails are partially furled. Warner s Annular Sail Windmill. Messrs Warner of Cripplegate (London) make a windmill somewhat similar to American mills. The shut ters or vanes consist of a frame covered with canvas, and these are pivoted between two angle-iron rings so as to form an annular sail. The vanes are connected with spiral springs, which keep them up to the best angle of weather for light winds. If the strength of the wind in creases, the vanes give to the wind, forcing back the springs, and thus the area on which the wind acts dimin ishes. In addition, there are a striking lever and tackle for setting the vanes edge ways to the wind when the mill is stopped or a storm is expected. The wheel is kept face to the wind by a rudder in small mills ; in large mills a subsidiary fan and gear are used. Fig. 1 shows a large mill of this kind, erected in a similar manner to a tower mill. The tower is a framework of iron, and carries a revolving cap, on which the wind shaft is fixed. Behind is the subsi- FIG. 1. Warner s annular sail windmill.