VOL. XXXVII.] VHILOSOPHICAL TRANSACTIONS. 443 



The wheel lies with its 2 gudgeons or centres, a, b, on 2 brasses in the 

 pieces mn, which are 2 large 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 mo, and kept in their places by 2 arching studs, fixed in the stock l, 

 through 2 mortises in the lever mn. 



By these levers the wheel is made to rise and fall with the tide, which is per- 

 formed in the following manner. The levers mn are It) 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 n, 10 feet. To the bottom of the arch n is fixed a strong 

 triple chain p, made in the fashion of a watch-chain, only the links arched to 

 a circle a foot in diameter, with notches or teeth, to take hold of the leaves 

 of a pinion of cast iron a, 10 inches in diameter, with 8 teeth in it moving 

 on an axis. The other loose end of this chain has a large weight hanging to 

 it, to help to counterpoise the wheel, and preserve the chain from sliding on 

 the pinion. On the same axis is fixed a cog-wheel n, 6 feet in diameter, with 

 48 cogs: to this is applied a trundle or pinion s, of 6 rounds or teeth; and on 

 the same axis is fixed t, a cog-wheel of 51 cogs, into which the trundle v, 

 of 6 rounds, works; on whose axis is a winch, or windlass, w, by which one 

 man, with the two windlasses, raises or lets down the wheel, as there is 

 occasion. 



And because the fulcra of these levers, mn, are in the axis of the trundle k, 

 viz. at M or x, in what situation soever the wheel is raised or let down, the 

 cog-wheel ii, is always equidistant from m, and works or geers truly. 



By means of this machine the strength of an ordinary man will raise about 

 50 ton weight. 



II is a cog-wheel fixed near the end of the great axis, 8 feet in diameter, 

 and 44 cogs working into a trundle k, 4-i- feet in diameter, and 20 rounds, 

 whose axis or spindle is of cast iron 4 inches in diameter, lying in brasses at 

 each end, as at x. 



zz is a quadruple crank of cast iron, the metal being 6 inches square, each 

 of the necks being turned 1 foot from the centre, which is fixed in brasses at 

 each end in two head stocks, fastened down by caps. One end of this crank 

 at Y is placed close abutting to the end of the axle-tree x, where they are at 

 those ends 6 inches in diameter, each having a slit in the ends, where an iron 

 wedge is put, one half into the end x, the other half into y, by means of 

 which the axis x turns round the crank zz. 



The 4 necks of the crank have each an iron spear, or rod, fixed at their 

 upper ends to the respestive libra or lever, a 1, 2, 3, 4, within 3 feet of tlie 

 end. These levers are 24 feet long, moving on centres in the frame bbbb; at 

 3 L 2 



