28 THE PHYSICAL GEOGRAPHY OF THE SEA. 



an inclined plane, whose submarine ascent is not less than ten 

 inches to the mile. 



The Niagara is an "immense river descending into a plain." 

 ' But instead of preserving its character in Lake Ontario as a dis- 

 tinct and w^ell-defined stream for several hundred miles, it spreads 

 itself out, and its waters are immediately lost in those of the lake. 

 Why should not the Gulf Stream do the same ? It gradually en- 

 larges itself, it is true ; but, instead of mingling with the ocean by 

 broad spreading, as the " immense rivers" descending into the 

 northern lakes do, its waters, like a stream of oil in the ocean, 

 preserve a distinctive character for more than three thousand miles. 



11. Moreover, while the Gulf Stream is running to the north 

 from its supposed elevated level at the south, there is a cold cur- 

 rent coming down from the north ; meeting the warm waters of 

 the Gulf midway the ocean, it divides itself, and runs by the side 

 of them right back into those very reservoirs at the south, to which 

 theory gives an elevation sufficient to send out entirely across the 

 Atlantic a jet of warm w^ater said to be more than three thousand 

 times greater in volume than the Mississippi River. This current 

 from Baffin's Bay has not only no trade-winds to give it a head, 

 but the prevailing winds are unfavorable to it, and for a great part 

 of the v/ay it is below the surface, and far beyond the propelling 

 reach of any wind. And there is every reason to believe that this 

 polar current is quite equal in volume to the Gulf Stream. Are 

 they not the effects of like causes ? If so, what have the trade- 

 winds to do with the one more than the other ? 



12. It is a custom often practiced by seafaring people to throw 

 a bottle overboard, with a paper, stating the time and place at 

 which it is done. In the absence of other information as to cur- 

 rents, that afforded by these mute little navigators is of great 

 value. They leave no tracks behind them, it is true, and their 

 routes can not be ascertained. But knowing where they were 

 cast, and seeing where they are found, some idea may be formed 

 as to their course. Straight lines may at least be drawn, show- 

 ing the shortest distance from the beginning to the end of their 

 voyage, with the time elapsed. Captain Beechey, R. N., has pre- 

 pared a chart, representing, in this way, the tracks of more than 

 one hundred bottles. From it, it appears that the waters from 

 every quarter of the Atlantic tend toward the Gulf of Mexico and 



