212 PROPERTIES OF AIR 



Proposition 1 . Any part of afluid at rest, pres- 

 ses and is pressed equally in every direction. 



Proposition 2. When the surface of a fluid 

 is level, the whole mass will be at rest. 



Proposition 3. The weight of fluids is as 

 their quantities of matter. 



It is proper for me to observe, that I have 

 placed these fundamental propositions in the 

 order which they ought scientifically to be 

 placed, and, for that purpose, have inverted the 

 mannerin which theyare generally placed, which 

 is as follows : 



Prop. 1. The weight of fluids, is as their 

 quantities of matter. 



Prop. 2. When the surface of a fluid is level, 

 the whole mass will be at rest. 



Prop. 3. Any part of a fluid at rest, presses 

 and is pressed equally in every direction. 



Although these propositions are laid down 

 as fundamental principles, and the truth of 

 them is attempted to be proved, with all the 

 display of mathematical demonstration, I, ne- 

 vertheless, contend, that whoever compares the 

 first and the third together, will be immediately 

 compelled to acknowledge, that they are alto- 

 gether at variance with each other. If the 

 pressure or weight of fluids, is in proportion to 

 the perpendicular height, or altitude thereof; 

 or to their quantities of matter ; how are these 

 assertions, I would ask, to be reconciled with 



