LECTURE IV. 



EXPERIMENTAL PHILOSOPHY. 



HYDROSTATl CS. 



THE word which stands as the title of this lec- 

 ture, implies simply the science which relates to 

 the weight of water compared with that of other 

 bodies ; but the science, as now taught and cul- 

 tivated, treats not only of the weight and pres- 

 sure, but of every thing relative to the action 

 and mechanical properties of the dense or in- 

 compressible fluids, such as water, &c. 



Though water is generally regarded as in- 

 compressible, yet it is not entirely so, since it is 

 capable of transmitting sound, which proves that 

 it is elastic, and every elastic body must be com- 

 pressible. To prove the fact, however, the Floren- 

 tine academicians filled a globe of gold perfectly 

 full with water, and afterwards closed the orifice 

 by a tight screw. The globe was then put into 

 a press of considerable force ; it was a little flat- 

 tened at the sides by the force of the press, but 

 was proportionably extended in other parts of its 

 surface, so that it was concluded that the water 

 did not occupy less space than before. On press- 

 ing it still harder, the water was made to exude 

 through the 'pores of the gold, and adhered to 



