38 Experimental PhilosopJiy. [Lecture 4. 



aid of mathematical theory, fluids have been sup- 

 posed to be constituted of small globules, as re- 

 presented in fig. 10. If therefore any one of the 

 columns, 1, 2, 3, 4, or 5, be removed, its place 

 will be immediately supplied by a number of 

 small globules, which will roll from, the other 

 columns and fill up the vacancy, and consequently 

 the superficies of the whole will presently sink to 

 the same level; as will be found to be the case in 

 a vessel filled with shot, with bullets, or any 

 small round and smooth bodies. On the other 

 hand, supposing these particles to have a very 

 smooth and slippery surface, so as to move with 

 very great ease upon one another, if the vessel 

 which contained them were not full, and any ad- 

 dition were made to the quantity, this addition 

 would displace a number of other particles, which 

 would roll round, and restore the level at the 

 surface. Thus, in fig. 9, we will suppose a per- 

 pendicular pressure to be made by the column 

 ik, opposite to the point d; but as it, can proceed 

 no further than that point, because of the bottom 

 of the vessel, the pressure will be directed late- 

 rally towards the sides efof the vessel, in such 

 a manner that, if there were any aperture then 

 in the vessel, the fluid would flow out : as that 

 however is not the case, the particles g and h 

 being restrained by the side of the vessel, those 

 which compose the lateral column force them- 

 selves between these particles g and h, and h 

 will be raised towards the surface of the fluid, 



