Scientific amusements . estimated from a height of45 miles to 212 miles in an attenuated form ; but perhaps100 miles high would be a fair estimate of the height towhich our atmosphere extends. The pressure of such an enormous body of gas is verygreat. It has been estimated that this pressure on theaverage human body amounts to fourteen tons, but beingbalanced by elastic fluids in the body, the inconvenience isnot felt. The Weight of Air can easily be ascertained,though till the middle of the seventeenth century the airwas believed to be without weight. The following ex»periment will ptovie the
Scientific amusements . estimated from a height of45 miles to 212 miles in an attenuated form ; but perhaps100 miles high would be a fair estimate of the height towhich our atmosphere extends. The pressure of such an enormous body of gas is verygreat. It has been estimated that this pressure on theaverage human body amounts to fourteen tons, but beingbalanced by elastic fluids in the body, the inconvenience isnot felt. The Weight of Air can easily be ascertained,though till the middle of the seventeenth century the airwas believed to be without weight. The following ex»periment will ptovie the weight of air. Takfe an GH-dittary 72 GASES AND LIQUIDS. balance, and suspend to one side a glass globe fitted witha stop-cock. From this globe extract the air by means ofthe air-pump, and weigh it. When the exact weight is. Weighing the air. ascertained turn the stop-cock, the air will rush in, and theglobe will then pull down the balance, thus proving that airpossesses weight. The experiments of Torricelli and OttoVon Guerike, however, demonstrated that the air has weight THE AIR-PUMP. 73
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Keywords: ., bookcentury1800, bookdecade189, booksubjectscientificrecreations
