181. Windmill.
Wind.—Wind engines or mills have the decided advantage of being very economical, but are necessarily irregular in action and are only suited for high or open situations. They are rarely of practical use in towns, or where buildings, trees, &c., exist in any size or number, but where the situation is favourable they are to be highly commended for several purposes, pumping especially. They invariably take the form of a strong vertical structure or framework, surmounted with the mechanism to which the sails are attached, and from which is carried a shaft to the base (somewhat similar to Miller’s wind mills). Warner & Co., of Cripplegate, London, make a specialty of these motors, adapted for numberless purposes, and in which high powers are attainable. Fig. 181 shows an annular sailed wind engine, as applied for pumping; it will be understood that the engine can be stood immediately over the well, or it can be fixed in some more convenient and suitable position and connected with the well by shaft or by pipe.
The illustration will acquaint the reader with details more fully, and it will be noticed that these engines are self-regulating, i.e. means are provided to shift the position of the sail automatically as the wind varies; in the larger sizes “striking” gear is fitted for setting the blades of the sail out of the wind when needed. The illustration represents a No. 2 Warner’s wind engine, with 10 ft. sail, price 25l., including pump and timber supports; this size is capable of raising 240 gal. of water per hour 50 ft. high, but the sizes may be smaller or larger as the requirements demand; after the first cost the expense is comparatively ended, as only lubrication is needed.
Water.—Water wheels also have the advantage of being economical, and greater reliance can be placed on the regularity of water than in wind power; but it is only for those that have rivers, streams, &c., at disposal. Those that are favourably situated cannot too highly prize the power they possess, as very regular and very high powers can be obtained at will and at a moment’s notice, free of cost (excepting first outlay), and requiring scarcely any attention.
182. Water wheel.
Water wheels are of three kinds, viz. overshot, breast, and undershot; as the names signify, the water flows over, or to the breast, or under the wheel, the difference in construction consisting in the shape of the blades on the wheel’s circumference. The first of the three is undoubtedly the most powerful, as not only is the impulse of the flowing water imparted to the blades, but the blades themselves are so constructed that they retain a portion of the water for about a third of a revolution and thus very materially assist by gravitation; the breast wheel is driven by the weight of the water retained by the blades only, and the undershot wheel is driven by the impulse of the water flowing beneath.
Warner & Co., of Cripplegate, London, make a specialty of these machines. Fig. 182 shows an overshot wheel adapted for pumping pure water from a well, and delivering it at any high elevation while being worked by a stream of impure water.
There is practically no limit to the size and power of these wheels, a 50 ft. wheel giving as high as 54 horse-power. The illustration is a No. 1 Warner’s galvanised iron overshot wheel, price 25l., including framework and double action pump, with air vessel complete, capable of lifting ½ gal. of water per minute 60 ft. high through 400 ft. of delivery pipe. The power of these wheels is not only increased as the diameter increases, but also by increasing the width of the blades; for instance, a Warner’s wrought iron overshot or high breast wheel of 20 ft. diameter with blades 3 ft. wide, develops 11 horse-power, and the same diameter with 6 ft. blades very naturally gives double (22 horse-power), but with only about 30 per cent. increased cost.