Scientific Intelligence — Hydrology. 191 



in the verification of an emperical law, even from nearly ninety luna- 

 tions, it seems very distinctly to negative the asserted law which gave 

 rise to the inquiry. — Proceedings of the Royal Society for March 

 1851. 



HYDROLOGY. 

 3. Action of Waves, — In the course of a paper read before the 

 Society of Arts, on " Artificial Break-waters," by Mr A. G. Findley, 

 we find some interesting facts concerning the force and action of waves 

 of the ocean. The dynamic force exerted by sea waves is greatest 

 at the crest of the wave before it breaks, and its power in raising 

 itself is measured by various facts. At Wasberg, in Norway, in 

 1820, it rose 400 feet, and on the coast of Cornwall, in 1843, 300 

 feet. The author cites numerous other cases, shewing that the waves 

 have sometimes raised a column of water equivalent to a pressure of 

 from three to five tons to the square foot. He also proved by a 

 table, that the velocity of the waves depends on their length ; — that 

 waves of from 300 to 400 feet in length from crest to crest, travel 

 with a velocity of 20 to 27i miles an hour, and this, whether they 

 are 5 or 54 feet in total height. Waves travel very great distances, 

 and are often raised by distant hurricanes, having been felt simul- 

 taneously at St Helena and Ascension, though 600 miles apart, and 

 it is probable that ground- swells often originate at the Cape of Good 

 Hope, 3000 miles distant. Nor do waves exert their force at or 

 near the surface only, one instance being mentioned where a diving 

 bell at the depth of eight fathoms was moved 5 feet laterally in 

 calm weather. The motion of " shingle" depends on the direction 

 in which the surf strikes the shore, which is influenced by the direc- 

 tion of the wind, and this is shewn from observations on the French 

 coast to be in the ratio of 229 days from western quarters, to 132 

 days from eastern quarters. At the British Association, Mr Steven- 

 son made a statement of the result of certain observations made by 

 him on the force of waves with reference to the construction of 

 marine works. The result of the experiments made gives a force of 

 about 1^ ton per square foot for the German Ocean, and of 3 tons 

 for the Atlantic Ocean. The experiments from which these results 

 were obtained were made at the Bell Rock and Skerryvore Light- 

 houses. — American Annual of Scientific Discovery., 1851, p. 160. 

 4. On the Alteration which Well-water undergoes. By M, C. 

 Blondeau. — The analysis which the author has performed on the 

 water of a great number of the wells of Ilhodez, has led him to adopt 

 the following conclusions : — 



1. Well-water may be altered by two causes: by the presence of 

 mineral salts held in solution, and by that of animal matters. 



2. The mineral substances which occur in solution are silica, alu- 

 mina, carbonates and phosphates of lime and magnesia, potash, 

 alum, chlorides of calcium, magnesium, and sodium, with nitrates of 

 the same bases. These different substances are not hurtful to the 



