55'2 CURRENTS, GULPM-STREAMS, 



ice may be destroyed in one stormy season than is formed in several 

 winters, and its accumulation thus prevented." 



This evidence clearly proves that the sun's influence at the poles, 

 so far from being equal to produce a constant and uniform effect, 

 creating an impulse extending its effect to the remotest parts of our 

 globe, and a daily elevation of several feet to the waters of the 

 ocean, is not sufficient in the hottest period of summer to diffuse 

 a sensible thaw; and thus we are convinced that a few plain and 

 simple facts are of much greater avail than a multitude of fanciful 

 conjectures. 



[Phil. Mag. FO/.VIII.] 



SECTION VII. 



Currents, Gulph-strcams 9 and Temperature of the Sea. 



BESIDES the common and periodical tides described and ex- 

 plained in the preceding section, a variety of local currents are 

 frequently met with in different seas, on different parts of the ocean, 

 for the most part not far from land. These are usually and per- 

 haps correctly ascribed to particular winds, but they do not always 

 appear to issue from this cause, nor is it easy to ascertain their 

 origin; occasionally indeed they have been traced below the surface 

 of the water, running in a contrary direction to the stratum of 

 water above, and in such cases undoubtedly the result of something 

 very different from winds or monsoons. This last has often been 

 ascribed, and at times, perhaps, correctly, to the immense masses of 

 polar ice, producing a greater decree of cold in the under than in 

 the upper water: whence Count Rumford suspects there is an under 

 current of cold water flowing perpetually from the poles towards 

 the equator, even where the superior water flows from the equator 

 towards the poles; and he thus endeavours to account for the great 

 inferiority of temperature which is frequently found in deep and 

 superficial soundings of the same space of water. 



The following ingenious article inserted in the Philosophical 

 Transactions for 1684, by Dr. Smith, furnishes us with various in- 

 stances of under- currents, and at the same time accounts for them 

 upon a different principle. 



" In the Offing, between the North and South Foreland, it runs 

 tide and half tide, that is, it is either ebbing water or flood on the 



