128 Quinby on the Blowing Machinery of a Furnace. 
Art. XVIl.—Investigation relative to the Blowing Ma- 
chinery of a Blast Furnace ; by Mr. A. B. QuinBy. 
THE proper construction of the blowing machinery of a 
blast furnace, is a subject that deeply interests many indi- 
viduals. I am not aware that any formule have ever been 
given to assist in planning such machinery. From the na- 
ture of the problem, it is easy to perceive, that there must be 
a relation between the quantity of water employed, the verti- 
cal height through which the water acts upon the wheel, the 
capacity of the air-pipe,* and the pressure under which the 
air is discharged. 
There is also a relation between the diameter of the air- 
time. 
Put P=number of cubic feet of water employed per minute. 
- -h=vertical height through which the water acts upon the 
wheel. 
d=diameter of the air-pipe. 
p=pressure (per sq. inch,) of air discharged per minute. 
=diameter of the cylinder or piston. 
L=length of the stroke. 
N =number of strokes per minute. 
M=volume (cubic feet) of air discharged per minute. 
Then, since the velocity with which the air issues under a 
pressure of 1 Ib. per square inch is known to be 20,726 feet 
per minute ;+ and since it is also known that the velocity va- 
ries a: square root of the pressure, we have for the velo~ 
city with which air will be discharged under the pressure p 
Ibs. per square inch, 20726 x /p. And since the pressure 
of 1 Ib. per square inch, gives a velocity of 20726 feet per 
minute, an air-pipe 1 inch in diameter, (under this pressure,) 
will discharge 113.04 cubic feet per minute. 
Now the volume discharged in a given time will evidently 
be in proportion to the square of the diameter of the air- 
* The air-pipe is the pipe from which the air is discharged into the tuyere 
of the furnace. 
t See Farrar’s Hydrodynamics, p. 382. 
