Atmospheric Pressure

the pres: sure exerted by the atmosphere, not merely downward, but in every direc. tion. It amounts to 14.7 pounds of weight on each square inch, which is often called in round numbers 15. On a square foot it is =2,160 pounds, or nearly a ton, It would act upon our bodies with crushing effect were it not that the pre ure, operating in all directions, produces an equilibrium. If any gas or liquid pre upon a surface with a force of 15 pounds on a square inch, it is generally described as having a pre ure of one atmosphere; it 60 pounds, of four atmospheres; if 120 pounds, of eight atmospheres, and so on.