28 



NOTES ON BRAZIL. 



No man who sails upon the ocean, and possesses the slightest degree 

 of curiosity, can avoid wishing to know what is the nature of its bottom, 

 and the depth at which it might be found. In general, however, he 

 must be satisfied with conjectures, founded only upon slight indications 

 of nature. To examine the British seas, the Adriatic, and even the 

 Mediterranean, in order to learn something about the Atlantic and Pacific 

 oceans, is like measuring the attics alone to ascertain the size and pro- 

 portions of a Palace. All small seas must be shallow ; and near rocky 

 shores the bottom must usually be irregular. Currents also, wherever 

 they exist, will wear for themselves channels deep and broad, in propor- 

 tion to their own violence, the time which they have been in existence, 

 and the softness of the materials upon which they Aow. But in the 

 larger expanses of water, where it is little disturbed by local circum- 

 stances, the bottom is probably more uniform and level. Where the 

 ocean is so deep as to maintain tranquillity in its lower waters amidst 

 violent tempests, if there be any such places, the bottom cannot be worn ; 

 it will generally speaking, be a sandy plain, broken into small undulations, 

 or interrupted by long ridges and detached masses of rock. The average 

 depth of the Atlantic, I apprehend, is much less than has been commonly 

 supposed ; because we now and then, although very seldom, fall in with 

 detached patches of discoloured water ; and there, most undoubtedly, the 

 ocean cannot be deep, nor its bottom hard ; and in all places where 

 animals of the Medusa tribe, or plants exist, unless when they are found 

 in currents, and do not float over their native beds, I am inclined to 

 consider them as indications that the bottom is not much beyond the reach 

 of our common sounding lines. 



Indeed the nodules floating in the Weedy -sea, which have been 

 mentioned before, point out an excellent and easy method of ascertaining 

 the greatest depth at which they could possibly grow. By knowing thei? 

 buoyancy, and the strength of the stalk nearest to the part which has 

 been separated from the parent-stem, we may discover the utmost 

 pressure which they could bear in still water, i. e. the utmost possible 

 depth of the spot on which they could flourish ; for the pressure of the 



