PHYSICAL PROPERTIES AND STATES OF MATTER 13 



and in consequence does not move at all. The experiment can 

 be varied by making one cylinder horizontal, while the other 

 remains vertical. In this case, also, if we push in the hori- 

 zontal piston we notice that the upright piston rises in just 

 the same manner as before, showing us that pressure is com- 

 municated in different directions. Finally, if we use a device 

 after the pattern of our illustration Fig. 8, and fill it with water, 

 when the piston working in the cylinder is 

 pushed down the jets spurt out equally 

 in all directions from the holes in the 

 globe, thus showing that the pressure is 

 communicated equally in all directions. 



Hydraulic Press. Reverting to our 

 first example in the last paragraph, and 

 glancing at Fig. 7, suppose that the sur- 

 face of the piston on the right had been 

 twice as great as the other, and that, as 

 before, weights of 10 Ibs. had been placed 

 upon each piston. They will no longer 

 balance ; the right-hand weight is pushed 

 upwards, and to bring about a balance it 

 would be found necessary to put 20 Ibs. 



on the larger piston. Similarly, had the right-hand piston been 

 a hundred times larger, we should have to put 1,000 Ibs. upon it 



to bring about a balance. 

 The upAvard force, then, 

 is proportional to the ex- 

 tent of the surface of the 

 piston. This principle, 

 which seems so different 

 from what we should 

 naturally expect, is referred 

 to as the Hydrostatic Para- 

 dox, and is utilised in the 

 Hydraulic Press, called, 

 after its inventor, the 

 Bramah Press, which is 

 shown in Fig. 9. Here 

 we have exactly the con- 

 dition of things just described, two cylinders in connection, 

 with pistons fitted into them, one much larger than the other. 



FIG. 8. Equality of la- 

 quid Pressure. 



FIG. 9. Hydrauli 



