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ONE:A gravity wheel must have a diameter equal to the fall of water, or, to use the technical name, the height of the head. The speed at the periphery of the wheel cannot well exceed sixteen feet per second without losing a part of the effect by the wheel anticipating or overrunning the water. This, from the large diameter of the wheels, produces a very slow axial speed, and a train of multiplying gearing becomes necessary in order to reach the speed required in most operations where power is applied. This train of gearing, besides being liable to wear [38]and accident, and costing usually a large amount as an investment, consumes a considerable part of the power by frictional resistance, especially when such gearing consists of tooth wheels. Gravity wheels, from their large size and their necessarily exposed situation, are subject to be frozen up in cold climates; and as the parts are liable to be first wet and then dry, or warm and cold by exposure to the air and the water alternately, the tendency to corrosion if constructed of iron, or to decay if of wood, is much greater than in submerged wheels. Gravity wheels, to realise the highest measure of effect from the water, require a diameter so great that they must drag in the water at the bottom or delivering side, and are for this reason especially affected by back-water, to which all wheels are more or less liable from the reflux of tides or by freshets. These disadvantages are among the most notable pertaining to gravity wheels, and have, with other reasons��such as the inconvenience of construction, greater cost, and so on��driven such wheels out of use by the force of circumstances, rather than by actual tests or theoretical deductions.

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ONE:Mr. Capper admitted the fact as he glanced at them. They had been paid to him two days ago and by him passed on to a wholesale firm of upholsterers."Come quietly," the officer suggested. "If you want to commit suicide go on acting like that. And if you drag me down that won't save your life."

TWO:Fitting processes, being the final ones in constructing machinery, are more nearly in connection with its use and application; they consist in the organisation or bringing together the results of other processes carried on in the draughting room, pattern shop, foundry, and smith shop.

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THREE:One of the first things I have to deal with is also one of the most fearful I ever saw, and I only hope that I may never again witness the like of it."Till next time," he said. "It's all over with me. The pitcher has gone too often to the well, and it has got broken at last. And I deserved all I got--there is no question whatever about that."