10 /'A'A'.s.sr/.'/ nF A IJQI'ID AT ANY DEPTH. 



EXAMPLES. 



1. If the area of the piston <i !>< a square inch, and if it 

 be pressed by a force of 25 Ibs., find the pressure which will 

 be transmitted to a surface of 35 square inches. 



Ans. 875 Ibs. 



2. If the area of the piston be 3 square inches, and if the 

 pressure on it be 96 Ibs., find the pressure which will be 

 transmitted to a surface of 17.5 square inches. 



Ans. 560 Ibs. 



3. If the area of the piston be 2.5 sq. in., and if the press- 

 ure on it be 50 Ibs., what pressure will this transmit to a 

 portion of the surface of the vessel whose shape is circular 

 and whose diameter is one foot ? Ans. 2261.95 Ibs. 



10. Pressure of a Liquid at any Depth. Thus far 

 only the transmission of external pressures has been con- 

 sidered; we shall now determine the effects of the internal 

 pressure due to the weight of the particles of the liquid 

 itself. 



Let DAE be the surface of the E An 



liquid at rest, and take any point B, 

 in the liquid; draw BA vertically to 

 the surface, and describe a small cyl- 

 inder about BA with its base horizon- 

 tal. Imagine this cylinder to become E^g 

 solid (Art. 5). Then this solid body 

 is at rest under its own weight, the 

 pressure of the fluid on the end B, and 

 the fluid pressures on the curved surface. 



The fluid pressures on the curved surface are all horizon- 

 tal (Art. 4), and the fluid pressure on the end B, and the 

 weight of the solid are vertical forces, and each group is 

 separately in equilibrium. Hence the fluid pressure on B 

 must be equal to the weight of the solid AB; if a be the 



