22 



HYDROSTATICS, 

 c 



the common runner and the syphon 

 runner feed the stream together, un- 

 til the lower hollow is drained. 



In some places the most absurd tales 

 are told, and believed by ignorant 

 people, respecting such springs ; their 

 flowing and ceasing are ascribed to 

 witchcraft; and designing men have 

 sometimes taken advantage of the 

 credulity of others, and gained credit 

 for themselves, by foretelling the re- 

 turn of the spring after it had ceased, 

 or pretending to stop it when it was 

 running. Some notions connected 

 with superstitions of this kind are 

 adverted to in the account given of 

 an intermitting or rather a variable 

 spring, at Layw r ell, near Torbay, in 

 Devonshire, by Dr. Atwell, the' first 

 person who distinctly explained these 

 appearances by the nature of the sy- 



hon. " It is a long mile (says he) 

 istant from the sea, upon the north 

 side of a ridge of hills lying between it 

 and the sea, and making a turn or 

 angle near this spring. It is situated 

 in the side of those hills, near the 

 bottom, and seems to have its course 

 from the S.W. towards the N.E. There 

 is a constantly running stream which 

 discharges itself near one corner, into 

 a basin, about eight feet in length, and 

 lour feet and a half in breadth, the out- 

 tet of w r hich is at the furthest end from 

 the entrance of the stream, about three 

 feet wide, and of a sufficient height. 

 This I mention, that a better judgment 

 may be made of the perpendicular rise 

 of the water in the basin at the time of 



the flux or increase of the stream. 

 Upon the outside of the basin are 

 three other springs, which always run, 

 but with streams subject to a like re- 

 gular increase and decrease with the 

 former : they seem indeed only branches 

 of the former, or rather channels dis- 

 charging some parts of the constantly 

 running water, which could not empty 

 itself all into the basin ; and, therefore, 

 when, by means of the season or wea- 

 ther, springs are large and high, upon 

 the flux or increase of this fountain, 

 several other little springs are said to 

 break forth, both at the bottom of the 

 basin and without it, which disappear 

 again upon the ebb or decrease of the 

 fountain. All the constant running 

 streams put together, at the time I saw 

 them, were, I believe, more than suffi- 

 cient to drive an overshot mill, and the 

 stream running into the basin might be 

 one-half of the whole. I had made a 

 journey, purposely to see it, in company 

 W 7 ith a friend ; when we came to the 

 fountain, we were informed by a man, 

 working just by the basin, that the 

 spring had flowed and ebbed about 

 twenty times that morning, but had 

 ceased doing so about half an hour be- 

 fore we came. I observed the stream 

 running in the basin for more than an 

 hour, by my watch, without perceiv- 

 ing the least variation in it, or the 

 least alteration in the height of the sur- 

 face of the water in the basin ; which 

 w r e could observe with great nicety, by 

 means of a broad stone laid in a shelv- 

 ing position in the water. Thus disap- 



