114 Things not generally Known. 



which it yields on boiling. Its density is considerably greater 

 than that of the Red Sea. One can hardly get the whole body 

 below the surface : in a sitting position the head and shoulders 

 will remain above the water, such is the strength of the brine ; 

 and on coming to the shore the body is covered with an incrus- 

 tation of salt in tine crystals. During summer the lake throws 

 on shore abundance of salt, while in winter it throws up Glau- 

 ber salt plentifully. " The reason of this," says Lieutenant 

 Gunnison, " is left for the scientific to judge, and also what 

 becomes of the enormous amount of fresh water poured into it 

 by three or four large rivers, Jordan, Bear, and Weber, as 

 there is no visible effect." 



FOECE OF RUNNING WATER. 



It has been proved by experiment that the rapidity at the 

 bottom of a stream is every where less than in any other part of 

 it, and is greatest at the surface. Also, that in the middle of 

 the stream the particles at the top move swifter than those at 

 the sides. This slowness of the lowest and side currents is pro- 

 duced by friction ; and when the rapidity is sufficiently great, 

 the soil composing the sides and bottom gives way. If the water 

 flows at the rate of three inches per second, it will tear up fine 

 clay ; six inches per second, fine sand ; twelve inches per second, 

 fine gravel; and three feet per second, stones the size of an 

 egg. Sir Charles Lyell. 



THE ARTESIAN WELL OF GRENELLE AT PARIS. 



M. Peligot has ascertained that the Water of the Artesian 

 Well of Grenelle contains not the least trace of air. Subterra- 

 nean waters ought therefore to be aerated before being used as 

 aliment Accordingly, at Grenelle, has been constructed a 

 tower, from the top of which the water descends in innumer- 

 able threads, so as to present as much surface as possible to 

 the air. 



The boring of this Well by the Messrs. Mulct occupied seven 

 years, one month, twenty-six days, to the depth of 1794| Eng- 

 lish feet, or 194 feet below the depth at which M. Elie de 

 Beaumont foretold that water would be found. The sound, or 

 borer, weighed 20,000 lb., and was treble the height of that of 

 the dome of the Hdpital des Invalids at Paris. In May 1837, 

 when the bore had reached 1246 feet 8 inches, the great chisel 

 and 262 feet of rods fell to the bottom ; and although these 

 weighed five tons, M. Mulot tapped a screw on the head of the 

 rods, and thus, connecting another length to them, after fifteen 

 months' labour, drew up the chisel. On another occasion, this 

 chisel having been raised with great force, sank at one stroke 

 35 feet 3 inches into the chalk ! 



