104 



THE WATEn RAii. 



Manner of ils 

 acting. — An 

 horizontal co- 

 lumn of water 

 is suffered to 

 Tun out thro' 



IS built at II, and receives the support of the head of the fan;, 

 so as to render the whole of the machinery as firm as possible 

 'i'lus is easily accomplished by laying H with very large stones, 

 or by placing them against immovable obstacles. - 



I shall now speak of the action of the machine. 



If the valve G open, the water filling the long tunnel BCDO 

 will issue out, and disperse itself with a velocity continually in- 

 creasing; for this water will fall, and it is well known that 



a valve, which falling bodies acquire an increase of valocitv. 



shnts when a . ^ . . -^ 



certain velocity ^^^^ ^^ 8- certam velocity the force of the current will raise 



is acquired. the valve G, and the orifice will be closed. The whole of 

 Ine momen- , t i /• 



turn then drives ^'^^ cylinder of water included in the long tunnel BCDO w'iU 



watS'throu h ^'^^" ^^ suddenly stopped ; but the active force -with which it 

 another valv* is impelled cannot be annihilated : this therefore will exert a 

 rl *uire?^^^'°" pressure against the whole of the inside of the tunnel, and as 

 this is very strong, the pressure will impel a certain quantity of 

 water through the aperture I, which the valve, raised by the 

 w :tter itself, leaves open. Consequently water will enter into 

 the bell It. The active force existing in the cylinder of \Vater 

 being thus expended, the pressure, to which the valve G had 

 yielded, will cease to exist, and the elasticity of the metal, as- 

 sisted by the weight of the valve, will cause it to descend 

 again. The aperture being then open, the water will begin 

 again to flow, and these operations will be repeated as long as 

 there is any water before the dam. 



This succession of actions, which has taken me so long to 

 dea^ribc, passes in a very short space of time ; frequently in 

 less than half a second, sometimes in three seconds, according 

 Eec«,ndtt) three, j^ ^^^ dimensions and conditions of the machine : but be the 

 time what it may, all that I have said actually takes place, 

 beside other events, that it is not necessary to mention here. 



It is obvious then, that every time the stopping valve 

 tlofcs, a poition of the water which was in motion will pass 

 into the bell. This will soon be sufficient in quantity for the 

 extremity of the ascending pipe to be immersed in it, and then 

 the air over the water will have no communication with th« 

 atnw)^phere. If the machine continue its action, the water 

 entering into the reseryoir will compress this air, and this aif, 

 The water may reacting on the surface of the water, will force it to ascend in 

 bcnusedtoany ^^^ ^.^^ j.^^^^ ^^ ^j^^ greatc ii height thai canbe given to it. 



The effect is 

 produced by 

 alternations 



— from half a 



In 



