PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 579 



ward. As far as I have gone into this explanation, I have merely 

 illustrated the true doctrines of my predecessors, without advanc- 

 ing any peculiar ideas of my own. The following views are of a 

 different character, having nothing to recommend them but their 

 own obvious merits. 



New Theory of the Ocean Currents — Two Classes of Currents. 



It has been assumed by all writers on the ocean currents that 

 the water always leaves the equatorial, and also the polar regions, 

 possessing the same rate of easterly velocity as the earth does in 

 the latitude from which the current flows. This is not only a great 

 mistake, but it has been the source of nearly all the errors with 

 which this subject has been embarrassed. The truth is that there 

 are two distinct classes of currents in the ocean, one of which may 

 be denominated local, and the other elliptical. '. 



The explanation of the currents already made applies only to 

 the local currents. The elliptical currents have hitherto never 

 been recognized as a distinct class, and the theoretical principles 

 upon which they depend have been entirely overlooked. The two 

 classes of currents have been strangely confounded together. The 

 elliptical currents, when noticed, have been regarded as ordinary 

 local currents, deflected out of their normal paths by accidental 

 ciixumstances. 



Cause of the Elliptical Currents. 



Prof Joseph Henry, of Washington, D. C, in an article in one 

 of the Patent Oflice Reports, says, in substance, that "that there 

 are five immense circuits, or whirls of ocean currents, two in the 

 north and south Atlantic, and two in the north and south Pacific, 

 similar in situation, and analogous in direction and motion. In 

 the Indian ocean another whirl or circuit exists of the same general 

 character." 



"It is not pretended," he remarks, "that the circular currents 

 can be continuously traced, but by attentively examining the maps 

 the general outlines and directions can be made out." Prof. Dana, 

 in his Manual of Geology, makes the same general statement, and 

 illustrates it by an engraving. 



While these distinguished writers thus admit that each o-reat 

 ocean possesses an elliptical current, no explanation of the fact has 

 been proposed, except that the currents, when moving north or 

 south in the manner already explained, are deflected out of their 

 normal directions, and driven into circular movements by adverse 



