40 PHYSICAL GEOGRArnT OF TEE SEA, AND ITS METEOROLOGY. 



to show, but observations to prove. Navigators, while diifting 

 along with the Gulf Stream, have lowered a boat to try the 

 surface current. In such cases, the boat would drift either to 

 the east or to the west, as it happened to be on one side or the 

 other of the axis of the stream, while the vessel herself w^ould 

 drift along with the stream in the direction of its course : thus 

 showing the existence of a shallow roof-current from the middle 

 towards either edge, which would carry the boat along, but 

 which, being superficial, does not extend deep enough to affect 

 the drift of the vessel. 



111. Drift matter sloughed off to the right. — That such is the case 

 (§ 110) is also indicated by the circumstance that the sea-weed 

 and drift-wood which are found in such large quantities along 

 the outer edge of the Gulf Stream, are rarely, even with the 

 prevalence of easterly winds, found along its inner edge — and 

 for the simple reason that to cross the Gulf Stream, and to pass 

 over from that side to this, they would have to drift up an 

 inclined plane, as it were; that is, they would have to stem this 

 joof-current until they reached the middle of the stream. We 

 rarely hear of planks, or wrecks, or of any floating substance 

 which is cast into the sea on the other side of the Gulf Stream 

 being found along the coast of the United States. Drift-wood, 

 trees, and seeds from the West India Islands, are often cast up 

 on the shores of Europe, but rarely on the Atlantic shores of this 

 country. 



112. Wliy so sloughed off. — We are treating now of the effects 

 of physical causes. The question to which I ask attention is, 

 Why does the Gulf Stream slough off and cast upon its outer 

 edge, sea-weed, drift-wood, and all other solid bodies that are 

 found floating upon it ? One cause has been shown to be in its 

 roof-shaped current; but there is another which tends to produce 

 the same effect ; and because it is a physical agent, it should 

 not, in a treatise of this kind, be overlooked, be its action never 

 so slight. I allude now to the effects produced upon the drift 

 matter of the stream by the diurnal rotation of the earth. 



113. Illustration. — Take, for illustration, a railroad that lies 

 north and south in our hemisphere. It is well known to engi- 

 neers that when the cars are going north on such a road, their 

 tendency is to run off on the east side ; but when tlie train is 

 going south, their tendency is to run off on the west side of the 

 track — i. e., always on the right-hand side. Whether the road be 



