Weight of one cubic foot of Pure Water.
| At 32° F. | = | 62.418 | pounds. | |
| At 39.1°F | = | 62.425 | „ | |
| At 62° | (Standard temperature) | = | 62.355 | „ |
| At 212° | = | 59.640 | „ |
The weight of a cubic foot of water is about 1000 ounces (exactly 998.8 ounces), at the temperature of maximum density.
The weight of a cylindrical foot of water at 62° F. is 49 lbs. (nearly). The weight of a cylindrical inch is 0.4533 oz.
There are four notable temperatures for water, namely,
| 32° F., | or | 0° C. | = the freezing point under one atmosphere. |
| 39.1° | or | 4° | = the point of maximum density. |
| 62° | or | 16°.66 | = the standard temperature. |
| 212° | or | 100° | = the boiling point, under one atmosphere. |
Water rises to the same level in the opposite arms of a recurved tube, hence water will rise in pipes as high as its source.
The pressure on any particle of water is proportioned to its depth below the surface, and as the side pressure is equal to the downward pressure.
Water at rest presses equally in all directions. This is a most remarkable property, the upward direction of the pressure of water is equal to that pressing downwards, and the side pressure is also equal.
Any quantity of water, however small, may be made to balance any quantity, however great. This is called the Hydrostatic Paradox, and is sometimes exemplified by pouring liquids into casks through long tubes inserted in the bung holes. As soon as the cask is full and the water rises in the pipe to a certain height the cask bursts with violence.