396 ADDITIONAL NOTICES. [June 27, 1859. 



3rd. The translation of tlie mass of the waves when tliey have not free 

 scope underneath, although the wind is moderate. 



4th. The number of metres in depth to which the action of the waves is 

 communicated. 



5th. The superiority of the effects of the real motion of the waves over the 

 littoral and tidal currents, with respect to the translation of detritus or ob- 

 structive materials. 



From the general system of ideas developed by the author we gather that 

 to attribute a motion to the liquid mass of waves is not conformable to the 

 hydrodynamic principles generally established. Thus the propositions con- 

 tained in his first, third, and fifth questions cannot be explained by the me- 

 chanical theory of fluids, but he demonstrates that this theory, often contra- 

 dicted by experience, leaves much to be desired if applied to the undulating 

 motion of the sea. To this effect the author has, in his Introduction^ given a 

 description of the hypotheses or theories promulgated by the distinguished 

 authors who have preceded him, whence results such a variety of views as to 

 give confidence in his own opinion. However, the author appears thoroughly 

 convinced that the above theory is based upon truth. Thus, when extraor- 

 dinary causes do not intervene, the elements established by that theory in the 

 phenomenon are not altered, and consequently the latter acts according to the 

 law established by the theory. 



But when a cause like that of a violent and long-continued wind alters the 

 pre-established system in the undulatory motion, the author cannot but admit 

 a notable motion in the liquid mass. He holds it to be indisputable that the 

 wind can communicate to the waves a real motion of translation on the sur- 

 face of the water, and his conclusions are not deduced from experiments made 

 in the quiet of the stud}^ but from facts verified in the immensity of the 

 sea. The author has therefore adduced a great number of such facts in the 

 twelfth paragraph. Besides which, reason suggests to him that a liquid mass 

 in equilibrium on one side, receiving continuous or intermittent impulses, 

 must also receive continuous motions of translation from the opposite part. 

 Now, if this argument and the whole series of facts collected are not sufficient 

 to convince any one of the important influence that a given force of wind has 

 upon the liquid mass, the author requires explanations of those extraordinary 

 translations experienced by ships in certain latitudes where the current is 

 known or where none exists (§ 13). The facts subsist ; we feel the necessity 

 of explaining them in order to prevent their fatal effects. But hitherto, as 

 far as the author knows, no one has occupied himself sufficiently with this 

 matter. 



In consequence of the materials gathered in the twelfth paragraph, it was 

 easy for the author to compile the contents of the thirteenth section ; and the 

 example of the English vessel Winchester and that of the French frigate 

 Venus, adduced in the above paragraph, are for him a clear explanation of the 

 sought-for cause of that extraordinary translation or drifting. The number 

 of examples, says the author, might be considerably increased, but, in a paper 

 bearing the simple title of ' Hints,' he thinks that what he has said on the 

 subject in §§ 12 and 13 may prove sufficient. Now, if this proposition, 

 which embraces the first question, somewhat differs from the theoretical law 

 of the undulatory motion, seeing that the powerful causes in certain cases 

 produce an alteration, he believes that, in these exceptional cases, the said 

 proposition may be admitted among those which are tolerably proved, and 

 therefore deserve to be seriously examined. When such exceptional causes 

 do not exist, namely, when the wave is not struck by a wind stronger than seven 

 metres of velocity in a second of time, the author agrees with the theory, and 

 therefore, in the second question, he does not admit a notable motion of trans- 

 lation in the waves, and he combats the contrary opinion of De Tessan, Alan 



