June 27, 1859.] ADDITIONAL NOTICES. 397 



Stevenson, Faoli, and De Coligny ; and, in the 15th paragraph, he adduces a 

 great number of facts to prove the mistake under which they labour. The author 

 therefore drawing a marked distinction between the state of a wave driven by 

 an impetuous wind and that of a wave acted on by a slight breeze, equally 

 combats the views of those authors who deny that there is any motion of 

 the particles of the liquid mass in waves, and those who always admit its 

 -existence. 



Let us now pass on to the proposition which forms the subject of the third 

 question. In the 19th paragraph the author begins to treat of the phenomena 

 which must occur when the wave strikes the bottom of the sea with its base. 

 The 20th paragraph describes this phenomenon, and the 21st shows its exist- 

 ence, deduced from a series of facts which he considers veiy conclusive. The 

 hypothesis that in the wave raised by the wind near the shore the same thing 

 may arise that occurs in the tidal wave (§ 21), seems to the author to have so 

 much analogy and probability that he believes himself obliged to admit one of 

 the following consequences : either that such hypothesis is the expression of 

 what actually takes place in nature, or that the reality, whatever it may be, 

 must be so nearly parallel to tiie truth as to admit of one mode of expression 

 common to both. 



It results therefore from what precedes, that if his proposition be not sus- 

 ceptible of any other explanation, it must be taken into consideration, other- 

 wise we should form a very restricted idea (on the authority of Sir J. F. W. 

 Herschel, says the author) of the merit and importance of the hypothesis ; but 

 following the relation of facts, he gathers his conviction that the hypothesis 

 by him presented amounts to a certainty. Nevertheless, he himself concludes 

 that it would not be useless to collect a greater number of proofs in order to 

 obtain universal assent to his convictions. 



From the remaining part of the 21st paragraph the author prepares the 

 arguments which are to serve him in supporting the proposition which forms 

 the fifth and last question. 



But before proceeding to it he stops to prove the volume and velocity of 

 the waves, the depth to which their action is communicated, and what their 

 power may be. 



1'he coasts of islands and continents receive their configuration from the 

 mass of waters in motion. Some distinguished authors assert that it results 

 from the littoral or tidal currents ; Avhereas Mr. Cialdi believes that such 

 configuration is the work of the waves. The paragraphs 22, 23, and 24, re- 

 ferring to a long series of analogous proofs, treat of the volume of the waves, 

 their vigorous footing proving their immense power at depths hitherto not 

 acknowledged by the learned, and induce the author to conclude that the 

 waves are the principal instruments employed by nature in excavating and 

 filling up the shores of the sea.* With this important series of facts the 



* From the facts gathered by Mr. Cialdi it results that the waves can attain 

 11 metres (.36 feet English) in height, 20 metres (66 feet) of velocity in one 

 second of time, and 300 metres (984 fe et) of amplitude from crest to crest. Their 

 power near the surface of the sea is of 30,000 kilogrammes per square metre 

 (6145 lbs. per square foot English) ; their action is communicated still perceptibly 

 at the depth of 200 metres (656 feet) ; and when arrived at a bottom of 34 metres 

 (111 feet) of water they break. 



In the Mediterranean the waves attain only 9 metres (29*5 feet) in height, 

 10 (32 8 feet) metres of velocity in a second, and their power has been found, 

 7 metres above the surface of the sea, to amount to 16,000 kilogrammes per 

 square metre (3265 lbs. per square foot), which is still perceptible at a depth of 

 60 metres (197 feet). They begin in that sea to break when they meet the bottom 

 at a depth less than 12 metres (39 feet). 



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