HYDROSTATICS. 



11? 



FIG. 64. 



down the cylinder. The pressure thus received and transmitted by 

 the confined water expels the cork and throws a jet of water from 

 each aperture. (See Appendix D.) 



(&.) The explanation of this property of fluids may be seen by 

 reference to Fig. 64, representing five molecules of any fluid. If a 

 downward pressure be applied to 1, it 

 will force 2 toward the right and 3 tow- 

 ard the left, thus forming lateral pres- 

 sure. When thus moved, 3 will force 4 

 upward and 5 downward. Owing to the 

 freedom with which the molecules move 

 on each other, there is no loss by friction, 

 and the downward pressure of 5, the 

 upward pressure of 4, and the lateral 

 pressure of 2, will each equal the pres- 

 sure exerted by 1. It makes no difference with the fact, whether 

 the pressure exerted by 1 was the result of its own weight only, 

 this weight together with the weight of overlying molecules, o* 

 both of these with still additional forces. 



217. Pascal's Law. Pressure exerted any- 

 where upon a mass of 



liquid is transmitted, un- 

 diminished in all direc- 

 tions, and acts with the 

 same force upon all equal 

 surfaces and in a direc- 

 tion at right angles to 

 those surfaces. 



218. An Argument from 

 Pascal's Law. Fill with water 

 a vessel of any shape, having in 

 its sides apertures whose areas are 

 respectively as 1, 2 and 3, each 



aperture being closed with a piston. Suppose the pistons to move 

 without friction and the water to have no weight ; then there will 

 be no motion. Suppose that the piston whose area is represented 

 by 1 rests upon 1000 molecules of the water ; then will the piston 

 at 2 rest upon 2000, and that at 3 upon 3000 molecules of water. 

 If now a pressure of one pound be applied to the piston at 1, this 



FIG. 65. 



