xiv INTRODUCTION. 



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

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

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

 mates, 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. 



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 department of sci- 

 ence ; and the aim of the author is to present the gleanings from 

 this new field in a manner that may be interesting and instructive 

 to all, whether old or young, ashore or afloat, who desire a closer 

 look into " the wonders of the great deep," or a better knowledge 

 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 little work relates. It is by Count L. F. Marsigli, an Italian, and is 

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

 lated into Dutch by Boerhaave in 1786. 



The learned 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 

 divided 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 alter 

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

 The reason why this acid (iodine ?) is found in surface and not in deep-sea water is, 

 it is derived from the air ; but he supposes that the saltpetre that is found in sea wa- 

 ter, 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 

 ]>lants for their existence, or deposited upon the earth's crust, as it occurs on the 

 })lains 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 

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



1 Phil03ophical Transactions. 



