DIAM. GALL.
25 feet 3671
20 „ 2349
15 „ 1321
14 „ 1150
13 „ 992
12 „ 846
11 „ 710
10 „ 587
9 „ 475
8 „ 376
7 „ 287
6-1/2 „ 247
6 „ 211
5 „ 147
4 „ 94
3 „ 53
2-1/2 „ 36
2 „ 23
The contents of cisterns and tanks are estimated either in gallons or
in cubic feet. _The weight of water in any cistern or tank_ can be
ascertained by multiplying the number of gallons by the weight of one
gallon, which is 8-1/3 pounds, 8.333. For instance, taking the largest
cistern in the above table containing 3671 gallons: 3671 × 8.33 =
30579.43 lbs. (nearly).
_If the cistern is rectangular_, the number of gallons and weight of
water are found by multiplying the dimensions of the cistern to get the
cubical contents. For instance, for a cistern or tank 96 inches long,
72 inches wide, and 48 inches deep, the formula would be: 96 × 72 × 48
= 331,776 cubic inches.
As a gallon contains 231 cubic inches; 331,776 divided by 231 gives
1,436 gallons, which multiplied by 8.33 will give the weight of water
in the cistern. Fig. 594.
_For round cisterns or tanks_, the rule is: Area of bottom on inside
multiplied by the height, equals cubical capacity. For instance, taking
the last tank or cistern in the table: area of 24 inches (diameter)
is 452.39, which multiplied by 12 inches (height) gives 5527.6 cubic
inches, and this divided by 231 cubic inches in a gallon gives 23
gallons. Fig. 595.
_Rule for obtaining the contents of a barrel in gallons._ Take the
diameter at the bung, then square it, double it, then add square of
head diameter; multiply this sum by length of cask, and that product
by .2618 which will give volume in cubic inches; this, divided by 231,
will give result in gallons.