1847.] Hydraulics for Farmers. 295 



but if its velocity be considerable, the jet is carried to a distance, 

 ere it touches the ground. 



That the force which a running stream thus acquired may be 

 made to drive a portion of the liquid far above the source whence 

 it ilows, is obvious from several operations in nature. During a 

 storm of wind, long swelling waves in the open sea alternately 

 rise and fall, without the crests or tops of any being elevated 

 much above those of the rest; but when they meet from opposite 

 directions, or when their progress is suddenly arrested by the bow 

 of a ship, by locks, or other obstacles, part of the water is driven 

 to great elevations. 



The hydraulic ram raises water on precisely the same princi- 

 ples: a quantity of the liquid is set in motion through an inclined 

 tube, and its escape from the lower orifice is made suddenly to 

 cease, when the momentum of the moving mass drives up, like 

 the waves, a portion of its own volume, to an elevation much 

 higher than that from which it descended. This may be illus- 

 trated by an experiment familiar to most people. Suppose the 

 lower orifice of a tube (where the upper one is connected to a re- 

 servoir of water) be closed with the finger, and a very minute 

 stream be allowed to escape from it in an upward direction, the 

 tiny jet would rise nearly to the surface of the reservoir. It 

 could not of course ascend higher. But if the finger was then 

 moved to one side, so as to allow a free escape, until the whole 

 contents of the tube were rapidly moving to the exit, and the ori- 

 fice then at once contracted or closed as before, the jet would dart 

 far above the reservoir; for, in addition to the hydrostatic pres- 

 sure which (h'ove it up in the first instance, there would be a new 

 ibrce acting upon it, derivctl from the momentum of the water. 

 As in the case of a hammer of a few pounds weight, when at rest 

 on the anvil, it exerts a pressure on the latter w'ith a force due to 

 its weight only; but when in motion by the hand of the smith, it 

 descends with a force that is equivalent to the pressure of perhaps 

 a ton. 



At a hospital in Bristol, England, a plumber was employed to 

 convey water through a leaden tube, from a cistern in one of the 

 upper stories, to the kitchen below ; and it happened that the 

 lower end of the tube was burst nearly every time the cock was 

 used. After several attempts to remedy the evil, it was deter- 

 mined to solder one end of the smaller pipe immediately behind 

 the cock, and to carry the other end to as high a level as the wa- 

 ter in the cistern. And now^ it was found that on shutting the 

 cock, the pipe did not burst as before, but a jet of considerable 

 height was forced from the upper end of this new pipe. It there- 

 tore became necessary to increace its height, to prevent water es- 

 caping from it; upon which it was continued to the top of the 



