Page:Philosophical Transactions - Volume 037.djvu/10



HE Wheels are placed under the Arches of London-Bridge, and moved by the common Stream of the Tide-Water of the River Thames.

A B the Axle-tree of the Water-Wheel, 19 Feet long, 3 Feet Diameter, in which C, D, E, F, are four Sets of Arms, eight in each Place, on which are fixed G G G G, four Rings, or Sets of Felloes, in Diameter 20 Feet, and the Floats H H H, 14 Feet long and 18 Inches deep, being about 26 in Number.

The Wheel lies with its two Gudgeons, or Centers, A B, upon two Brasses in the Pieces M N, which are two great Levers, whose Fulcrum, or Prop, is an arched Piece of Timber L, the Levers being made circular on their lower Sides to an Arch of the Radius M O, and kept in their Places by two arching Studs fixed in the Stock L, through two Mortises in the Lever M N.

The Wheel is, by these Levers, made to rise and fall with the Tide, which is performed in this Manner. The Levers M N are 16 Feet long; from M, the Fulcrum of the Lever, to O the Gudgeon of the Water-Wheel, 6 Feet; and from O to the Arch at N, 10 Feet. To the Bottom of the Arch N is fixed a strong triple Chain P, made after the Fashion of a Watch-Chain, but the Links arched to a Circle of one Foot Rh