INTRODUCTION. xv 



Under this term will be included a philosophical account of the 

 winds and currents of the sea ; of the circulation of the atmosphere 

 and ocean ; of the temperature and depth of the sea ; of the won- 

 ders that are hidden in its depths ; and of the phenomena that dis- 

 play themselves at its surface. In shorty I shall treat of the econ- 

 omy of the sea and its adaptations — of its salts, its waters, its 

 climates, and its inhabitants, and of whatever there may be of gen- 

 eral interest in its commercial uses or industrial pursuits, for all 

 such things pertain to its Physical Geography. 



XLVIII. The object of this little book, moreover, is to show the 

 present state, and, from time to time, the progress of this new and 

 beautiful system of research, as well as of this interesting depart- 

 ment of science ; and the aim of the author is to present the glean« 

 ings from this new field in a manner that may be interesting and 

 instructive to all, w^hether old or young, ashore or afloat, who desire 

 a closer look into " the wonders of the great deep," or a better knowl- 

 edge as to its winds, its adaptations, or its Physical Geography.* 



* There is an old and very rare book which treats upon some of the subjects to 

 which this httle work relates. It is by Count L. F. Marsigli, a Frenchman, and is 

 called Natural Description of the Seas. The copy to which I refer was transla- 

 ted into Dutch by Boerhaave in 1786. 



The French count made his observations along the coast of Provence and Langue- 

 doc. The description only relates to that part of the Mediterranean. The book is di- 

 vided into four chapters : the first, on the bottom and shape of the sea ; the second, of 

 sea water ; the third, on the movements of sea water ; and the fourth, of sea plants. 



He divides sea water into surface and deep-sea water ; because, when he makes 

 salt from surface water (not more than half a foot below the upper strata), this salt 

 will give a red color to blue paper ; whereas the salt from deep-sea water will not al- 

 ter the colors at all. The blue paper can only change its color by the action of an 

 acid. The reason why this acid (idoine 1) is found in surface and not in deep-sea water 

 can be derived from the air ; but he supposes that the saltpetre that is found in sea 

 water, by the action of the sun's rays and the motion of the waves, is deprived of its 

 coarse parts, and, by evaporation, embodied in the air, to be conveyed to beasts or 

 plants for their existence, or deposed upon the earth's crust, as it occurs on the plains 

 of Hungary, where the earth absorbs so much of this saltpetre vapor. 



Donati, also, was a valuable laborer in this field. His inquiries enabled Mr. Trem- 

 bley^ to conclude that there are, " at the bottom of the water, mountains, plains, val- 

 leys, and caverns, just as upon the land." 



But by far the most interesting and valuable book touching the physical geography 

 of the Mediterranean is Admiral Smyth's last work, entitled " The Mediterranean ; 

 A Memoir, Physical, Historical, and Nautical. By Rear-admiral William Hen- 

 ry Smyth, K.S.F., D.C.L.," &c. London : John W. Parker and Son. 1854. 



* Philosophical Transactions. 



