.[ 373 1 
jl)at-boards> by yielding to the adion of the dream, 
Caufe the axle on which they are fixed to turn round, 
by means of feveral wheels, which take into each 
other, and give motion to the part deftined to pro- 
duce fome purpofed effed, as the mill-done in a 
corn- mi 11. 
The fize of the float-boards, the velocity with 
which the wheel is to turn, and the number of the 
float- boards to produce the greatefl poffible effed, 
are three main things I propofe to examine in the 
following inquiry. 
In the fird place I will fuppofe the total refinance 
which this wheel has to encounter, on the part of 
the machine, and which hinders it from moving fo 
fwift as the fir earn, to be exprefled by a weight tt, 
fufpended to the extremity of a cord fixed to the cir- 
cumference of a wheel whofe radius is d, and which 
has the fame axle as the float- board wheel, fo that 
the effed of the dream is to raife the faid weight sr„- 
as exprefled in Tab. XV. fig. i. I will likewife fup- 
pofe, that the dream, by its velocity, moves through v 
feet in one fecond of time, and that this velocity is 
the fame, though at different depths. 
§ II. After thefe fuppofitions, the firfl; thing that 
prefents, is to determine what fhould be the fize of 
the float-boards for the dream to be capable of 
railing the weight n r. with a certain determinate ve- 
locity. 
Let A A BB, jig. 2 . be one of the float-bords 
let into the axle AA, and placed vertically in the 
water, fo as to receive the perpendicular impulfe of 
the dream. Its horizontal length BB — (3 feet, its 
vertical height AB=i« feet, the velocity of the 
wheel 
