CT B57} 
N°. XXII. 
Inveftigation of the Power of Dr. BARKER’s, Mill, as 
amproved by JAMES RUMSEY, with a defexiption. of 
the Mill, by Wm. WARING. 
Teicipton of the Mill. Plate 4. Fig. 2. 
Read Sept. T. Is the rotatory; being a tube or trunk 
ae into which the water is conveyed by a pipe 
from the head H, through the neck N and collar C, to 
the apertures m, n, on contrary fides; where, by its re- 
action in pafling off, it occafions a forcible rotation round 
the axis or {pindle X P, which paffes through the lower 
millftone S and turns the upper one M, or effeéts other 
purpofes. 
Of the proper capacity of the pipe by which the water is 
conveyed from the head Hto the rotatory at N. 
Let e= the area of the water’s paflace at N 
h= the perpendicular height of H above N 
> us the’ perpendicular depth of any part of the pipe 
below H | 
= the area at the depth ubelow H 
Then, the areas in the feveral parts of the pipe (being in« 
verfely as the velocities) muft be in the inverfe fubdupli- 
cate ratio of the depths below the head; wherefore S=74. 
which gives x=ev"; fo that the pipe mnt widen towards 
the head H in the proportion of 1 to ¥2; and if the area 
at any given height be lefs than ey} the water will be ob- 
firuGed in its paflage. 
This theorem (x=ey*) alfo applies to the pipe of a 
fire-engine, &c. h being — height of the nozzle from the 
VOL. HI. Fs ee Bea, bottom 
