264 



THE SIPHON. 



poured into the pipe till the vessel and pipe are filled, a 

 very small pressure applied at A will raise a very great 

 weight upon DE, the weight lifted being 

 greater as DE is greater. 



Let Ic be the area of a horizontal section of 

 the pipe, K that of a section of the cylinder, 

 or that of DE, and p the pressure applied at 

 A. Then, from (1) of Art. 9, we have 



W 



k_ 

 K 



(1) 





Fig. 70 



Sen. Suppose the pipe AB to be extend- 

 ed vertically upwards, and the pressure at A 

 to be produced by means of a column of water above it, 

 formed by pouring in water to a considerable height, and 

 suppose the pipe to be very small, so that the pressure upon 

 the section A may be very small ; then, as this pressure is 

 transmitted to every portion of the surface DE that is equal 

 to the section A, the upward force produced on DE can be 

 as large as we please. To increase the upward force, we 

 must enlarge the surface DE or increase the height of the 

 column of water in the pipe, and the only limitation to the 

 increase of the force will be the want of sufficient strength 

 in the pipe and cylinder to resist the increased pressure. 

 By making the pipe AB of very small bore, and the height 

 DC of the cylinder very small, the quantity of water can be 

 made as small as we please. That is, any quantity of 

 fluid, however small, may be made to support any 

 weight, however great. This is known as the hydrostatic 

 paradox. 



141. The Siphon. The action of a siphon is an im- 

 portant practical illustration of atmospheric pressure. It is 

 simply a bent tube of unequal branches, open at both ends, 

 and is used to convey a liquid from a higher to a lower 

 level, over an intermediate point higher than either. 



