OF SOLIDS AND LIQUIDS. ' 245 



through it, and the bottle were sunk to a 

 great depth, that the unresisting nature of the 

 air, with relation to the pressure of the water, 

 would break the bottle as perfectly as if it were 

 placed under a mass of granite : and there is 

 no proof, more obvious of the weight of water 

 upon air, than the condensation which air un- 

 dergoes when it is confined in a bladder, and 

 sunk in water. 



These different facts, and a multitude of 

 others, which I might adduce, altogether prove 

 the density of water, with relation to the rarity 

 of the air; the pressure of weight in the one, with 

 respect to the unresisting nature of the other. 

 A bucket full of water in water, suffers no 

 weight, (provided the wood is of a medium den- 

 sity with the water ;) neither does the flood- 

 gate sustain any pressure, when the water on 

 the outside is at the same level as it is on the 

 inside. If an ocean of quicksilver were to be 

 placed on the outside of the flood-gate, it would 

 overcome the resistance of the water within it, 

 and the same effects would take place by the 

 action of the quicksilver on th gate, as took 

 place by the action of the water on the bottom 

 and sides of the bucket, while it was suspended 

 in the air. Cases such as these tend to showthat 

 the pressure which is produced by fluids, alto- 

 gether depends on the diminished resistance 



