258 A short Account of Horizontal Water-W heels. 
in the form of a wedge, the edge of which is perpendicular to the 
base, so that.a line drawn from the centre of the wheel to it, will 
form a right angle with that side of the cut which faces the cen- 
tre. Fig. 1. 
Within the cylinder is placed the horizontal wheel, with floats, 
and a perpendicular axis or spindle, which turns on a point in 
the centre. Figs. 1 and 2. 
The floats FF are rectangular planes, fixed round the edge of 
the wheel in planes passing through the centre, and perpendicular 
to the plane of the wheel. Their height is something greater 
than that of a cut, and their breadth rather more than its width: 
also their number may be about three times the number of cuts. 
But for the purpose of obtaining the most regular motion, the 
numbers of the cuts and floats ought to be prime to each other. 
Fig. 2. 
The cylinder is surrounded by a reservoir of water, supported 
by a circular wall, which, in low falls, may be equal to its depth. 
Fig. 1. 
The reservoir is filled, from the canal or river, by a stream 
flowing through a head or slit at the top of the outer wall, and 
at the bottom, the water flows through the cuts PP against the 
floats, and turns the wheel. Figs. | and 2. 
The width of the eylinder within, RR, is continued downwards 
below the floats FF, toa depth sufficient for permitting passages 
to be made under the reservoir, of sufficient capacity to take away 
the water as fast as it enters the inner cylinder. Fig. 2. 
The passages at the bottom of the machine, showing the 
escape of the water, appear in the plate, for the want of room, 
to occupy only half the circumference, but ought to be continued 
quite round. Fig. 2. 
In fig. 2, where part of a perpendicular section of the machine 
is represented, the passage of the water appears to be only on 
one side, but the opposite side is supposed to pass through one 
of the solids which supports the reservoir and wall. 
The wheel, to about half the radius, is open quite round the 
centre, for the purpose of permitting the free passage of the air; 
(this, in a large wheel, may be much more than half;) the re- 
mainder is solid, quite round, and curved or dished on the under 
side, for the purpose of turning the water downwards, and pre- 
venting it from rising above the wheel, as it passes from the 
float, ina thin sheet to the centre, where it forms a head, which 
by its pressure facilitates its escape. Fig. 2. 
According to the manner in which the floats are fixed in the 
wheel, they ought, in the figure, to be invisible; but are made to 
appear, for the purpose of showing the nature of the action of 
the water against them, Fig. J. f 
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