THE GULF STREAM. . 41 



41. That such is the case (§ 39) is also indicated by the circum- 

 stance that the sea-weed and drift-wood which are found in such 

 large quantities along the outer edge (§ 13) 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 Avere ; that is, they would have to stem 

 this roof-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 said to have been cast 

 up on the shores of Europe, but never, that I ever heard, on the 

 Atlantic shores of this country. 



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 ? 



42. 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. 



43. Take, for illustration, a railroad that runs north and south. 

 It is well known to engineers that when the cars are going north 

 on such a road, their tendency is to run off on the east side ; but 

 when the 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 in our 

 hemisphere. Whether the road be one mile or one hundred miles 

 in length, the effect of diurnal rotation is the same, and the tend- 

 ency to run off, as you cross a given parallel at a stated rate of 

 speed, is the same ; whether the road be long or short, the tend- 

 ency to fly off the track being in proportion to the speed of the 

 trains, and not at all in proportion to the length of the road. 



44. Now, vis inertice and velocity being taken into the account, 

 the tendency to obey the force of this diurnal rotation, and to trend 



