APPENDIX. 
WATER. 
One gallon of water weighs 8^ pounds and contains 231 cubic 
inches. One cubic foot of water contains 7^ gallons, 1,728 cubic 
inches, and weighs 62-| pounds. One cubic inch of water evaporated 
under atmospheric pressure is converted into approximately one 
cubic foot of steam. The height of a column of fresh water equal 
to 1 pound pressure per square inch is 2.31 feet. In usual computa- 
tion this is taken at 2 feet. 
To find the pressure in pounds per square inch of a column of 
water, multiply the height of the column in feet by 0.434. Approxi- 
mately every foot elevation is equal to one-half pound pressure per 
square inch, allowing for friction. 
Pressure of i rater for each foot in height. 
Feet in height. 
Pounds 
per 
square 
inch. 
Feet in height. 
Pounds 
per 
square 
inch. 
Feet in height. 
Pounds 
per 
square 
inch. 
1 
0.43 
.86 
2.16 
4.33 
15 
6.49- 
8.66 
10. 82 
17.32 
50 
21.65 
20 
70 
30.32 
5 
25 
80 . 
34.65 
10 
40 .. 
100... 
43.31 
To find the velocity in feet per minute necessary to discharge a 
given volume of water in a given time, multiply the number of cubic 
feet of water by 144 and divide the product by the area of the pipe 
in inches. Doubling the diameter of a pipe increases its capacity 
four times. A miner's inch of water is approximately equal to a sup- 
ply of 12 gallons a minute. 
Measurement of an open stream by velocity and cross section. — 
Measure the depth of the water at from 6 to 12 points across the 
stream at equal distances between. Add all the depths in feet and 
inches together and divide by the number of measurements. This 
will give the average depth, which when multiplied by the width will 
give the area of the cross section. 
The velocity of the stream can be found by laying off 100 feet 
along the bank and throwing a float into the middle, noting the 
time taken in passing over 100 feet. Do this a number of times and 
take the average. Then divide this distance by the time, and it will 
be the velocity at the surface. As the top of the stream flows faster 
57 
