98 Atmosphere. 



phere on every square inch of surface is 

 equal to 15lb. Again, it has been found 

 that the pressure of the atmosphere bal- 

 ances, in the case of pumps, &c. a column 

 of water of about 3 | feet high ; and the 

 cubical foot of water weighing just 100O 

 ounces, or 6~^.b. 34-| times 62-|, or 2158 

 Ib. will be the weight of the column of 

 water, or of the atmosphere, on a base of 

 a square foot; and consequently the 144th 

 part of this, or 15lb. is the weight of the 

 atmosphere on a square inch ; the same 

 as before. Hence Mr. Cotes computed, 

 that the pressure of this ambient fluid on 

 the whole surface of the earth, is equiva- 

 lent to that of a globe of lead of sixty miles 

 in diameter. And hence also it appears, 

 that the pressure upon the human body 

 must be very considerable ; for as every 

 square inch of surface sustains a pressure 

 of 15lb. every square foot will sustain 144 

 times as much, or 2160lb. then, if the 

 whole surface of a man's body be suppo- 

 sed to contain fifteen square feet, which 

 is pretty near the truth, he must sustain 

 15 times 2160, or 32400lb. that is near 

 14-| tons weight for his ordinary load* 

 By this enormous pressure we should un- 



