A short Account of Horizontal Water-Wheéls. 259 
To find what depth the bottom passages ought to be, it will 
be only necessary to know the breadth and depth of: the head 
through which the water flows into the reservoir, as the same 
quantity must pass both places in the same time. 
The perfection of this machine may be shown as follows : 
1. The floats being open on all sides, except that opposite 
the centre, will prevent as much as possible, any reaction against 
the water coming in. 
2. The space below the floats, and the passages from it, being 
always sufficient to take away the water as fast as it enters, will 
prevent any accumulation of tail water from impeding the floats. 
3. The velocity of the water being greater than that of the 
wheel, prevents any impediment by centrifugal force. 
4. The force of the water through the cuts, arises from its 
perpendicular pressure from the surface to the centre of force, 
and therefore is the greatest possible. 
5. The line of pressure against the floats, is as nearly perpen- 
dicular to their surface, and as near to the extremity of the ra- 
dius, as it is possible to make it act against the floats of a wheel, 
and therefore the pressure against them cannot be greater. 
6. The water acts against all the floats at the same time. 
7. The whole of the water acts against the floats. 
8. The water receives no check from the want of air. 
9. No water-wheel can move with less friction. 
Hence it must be evident, that these principles will give the 
greatest power that can possibly be obtained from the action of 
water upon a horizontal wheel : 
But as a wheel acting on these principles has never before 
been tried, it was thought most advisable to put it to the test by 
experiment, previous to making it public. A very complete and 
perfect model (or rather a little mill) has therefore been made 
by Messrs. Bramah and Sons, at their manufactory in Pimlico, 
near London. 
The Model 
stands on a base of two feet diameter, and its height is 53 inches. 
The outward cylinder, which supports the water in the re- 
servoir, is of cast iron. 
The inner cylinder, in which the wheel moves, is of wrought 
iron, and its lower end, through which the cuts or water pas- 
sages are made, is of brass. 
The depth of the reservoir is about 51 inches. 
The number of cuts or water passages is 24, and their depth 
one inch, 
The wheel and floats are of brass. . 
The diameter of the wheel is 12 inches, and the number of 
floats is 79, a prime number. 
R 2 A mae 
