On the Cause of Fresh Water Springs, Fountains, fyc. 175 



Let us suppose that a hole has been opened in the branch 

 B, a little below I b the level of the water at ebb ; the water 

 will then flow with a velocity that may be represented by 1, 

 but at high tide the water might be supported at the height 

 h, if the opening in the tube did not permit it to flow out, 

 and it then must flow with the same velocity as if pressed 

 under a column of fluid of that elevation. The quantity of 

 water so running may be as 3, 4, 5, &c. according to the 

 height of the tide ; and finally, it must continually and exactly 

 follow its oscillations. 



Such is our solution for the two problems proposed. 



To these considerations several might be added, for exam- 

 ple : Knowing the proportional densities of the fresh water 

 and the sea water, and the difference of the two levels, to de- 

 termine at what depth the subterranean stream empties it- 

 self in the ocean. If we calculate the particular case here 

 given, we shall find, the density of fresh water being repre- 

 sented by 1000, that of sea water by 1029 (Dr. Murray,) 

 the difference of the levels being fifteen feet, we shall find, 

 I say that the depth at which they join under ground must 

 be five hundred feet. 



Thence it follows, that if the junction of the two different 

 kinds of water should take place at five thousand feet, or 

 one mile, below the surface, the fresh water should rise at 

 one hundred and fifty feet ; if at fifty thousand feet, or ten 

 miles, as one thousand five hundred feet, &c. This I think 

 may account for the springs on high ground, and even at 

 the top of insulated mountains. 



Proceeding on, and drawing conclusions from the above 

 principle, if admitted, it explains why there are during winter, 

 places in our rivers, and each year the same, called air holes, 

 where the water is very transparent, and will never freeze. 



It seems that streams, rivulets and rivers under ground, 

 are as numerous as on the surface of the earth, that they 

 join together to form main streams, and that they are all di- 

 rected towards the sea, where they empty at various depths, 

 we may suppose also that there are lakes various in extent, 

 and then we shall be compelled to admit, that the tide must 

 not have a more apparent effect on the springs that are 

 opened at remote, or elevated points of the surface, than 

 the tide of the Ocean has on the Mediterranean and Black 

 sea, although in open commuication with them. 



And to conclude, it might throw some light on that phe- 

 nomenon related by voyagers, of spaces of several miles in 



