The 11'7nd (lifrs. 5, 6), which is of .1inerican make,. rotates in a horizontal plane. Ili Figure 5, A represents the outside shut ters which surround the wheel, a portion of which is cut away to show the perpendicular fans, B."Phese shutters, each of which rests upon a pivot, are concave on the inner side, and all are so connected at the top as to admit of being opened' and closed like the slat of a blind. Below is the walking-beam C, with pitman and crank connected. The crank is fas tened to the bottom of the wheel by a cast flange or by a shaft running entirely through the middle to the top of the wheel, and rests upon a hardened-steel step or bearing. Instead of employing a crank motion for running the machinery, the power may be obtained by gearing directly to the shaft at the bottom of the wheel. The rope seen at the right is attached to the shutters, and when weighted acts automatically with them in regulating the supply of wind to the wheel. The action of the wind upon the wheel is shown in the sectional view' given in Figure 6, in which sss represent sixteen outside shutters that open to admit the ind and close to shut it off; fff show the sixteen fans of the wheel upon which the wind acts. (The arrows denote the direction of the wind in passing through the wheel.) This it is seen that the wind acts upon almost every
part of the wheel at the same time, and nearly as great an impulse is given to the wheel as the wind strikes the fans in coming out of it as is given when the wind goes into it.
For the same reason that the question of cost is an important factor in the practical value of a motive machine, wind-wheels have been unable to compete with most other motors, notwithstanding the facts that wind is free and that running expenses are small in comparison with those for thermodynamic, or even hydraulic, motors. Vet they might be more generally employed if, in the majority of cases where they could be applied, it were not for the financial and technical disadvantages im posed by the uncertainty of the wind 'and the consequent interruption to the working machine. Wind-wheels are not very powerful motors, and in their working they are variable and intermittent; in good situations they will generally work, on an average, about one-third of the time. Small wind-wheels are useful on farms for grinding grain, sawing wood, and pumping water, for which latter purpose they are also largely employed at watering-stations on American railways.