HYDROSTATICS. 



429 



The Cause of reciprocating Springs, and of ebbing and 

 flowing Wells, explained. 



Let abed be a hill, within which is a large cavern 

 A A near the top, filled or fed by rains and melted 

 snow on the top a, making their way through chinks 



and crannies into the said cavern, from which proceeds 

 a small stream c c within the body of the hill, and issues 

 out in a spring at G on the side of the hill, which will 

 run constantly whilst the cavern is fed with water. 



From the same cavern A A, let there be a small 

 channel D, to carry water into the cavern B; and from 

 that cavern, let there be a bended channel EeF, larger 

 than D, joining with the former channel c c, as at^ before 

 it comes to the side of the hill : and let the joining aty* 

 be below the level of the bottom of both these caverns. 



As the water rises in the cavern B, it will rise as high 



tion. In this apparatus, which was contrived by Mr. Bramab, the 

 water is forced by a small pump into a barrel, in which it acts on a 

 much larger piston ; consequently this piston is urged by a force 

 as much greater than that which acts on the first pump-rod, as its 

 surface is greater than that of the small one. 



