1198
THEORY AM) PRACTICE OF ENGINEERING.
Book II.
feet velocity per second, and 6 feet for the current : when the river was 2 feet above lowwater, the wheel made 180 turns per hour: when it made 165 turns, the troughs wereplunged 30 inches; when from 216 to 240,they were only in the water 15 inches. Thegreat wheel had 124 cogs, and the lanternwhich it turned 1 5 trundles: the other lanternover which the chain of the inclined chapeletworked, had eight trundles, each of which passedone palette of the chapelet; giving 66 T 2 . palettesfor each turn of the great wheel, 180 of whichit made in an hour, giving a total of 11,904palettes, each of which brought up 290 cubicinches of water ; the whole producing in anhour 1997$ cubic feet raised 12 feet.
The vertical chain pumps employed at thebridge of Orleans gave for the useful effect ofeach man, during twenty-four hours, 139 cubemetres of water raised 1 metre : but many ex-periments have been since made, and it has beenfound that 128 cube metres of water raised a
END ELEVATION, ORLEANS BRIDGE.
metre is nearer the result. The daily action of a man working at the winch being 155cube metres of water raised the same height, the relation between the useful effect and theforce expended is 0*826. The vertical chain pump is, however, a very serviceable machine,as there is not more than one-fifth part of its force lost: the chain-pump is easily taken upand replaced, and can readily be repaired.
The great Bucket-wheel employed by Perronet at the construction of Neuilly Bridgewas 16 feet 6 inches in diameter, and 4 feet 6 inches in width, furnished with 16buckets and 118 cogs. 'The wheel with float-boards was 18 feet in diameter, and had128 cogs ; the float-boards, 20 feet in length and 3 feet in width, made an angle of 15 de-grees with the radius, to diminish the resistance of the water as they turned : generally thelanterns of 4 feet in diameter had 30 trundles, and the tree was 12 inches in diameter; thelength was regulated according to circumstances; some were 38 feet, and from 54 to 108