160 ANNUAL OF SCIENTIFIC DISCOVERY. 



and it will be seen that the great ocean is divided into five principal 

 basins. The Atlantic contains two, separated from one another by 

 the equator; the Pacific contains two also separated from one an- 

 other by the equator ; the other is formed by the Indian Ocean, lying 

 between India and Australia. Two circumpolar currents may also 

 be perceived, one of which goes round the north pole, and the 

 other round the south pole from east to west. The theory speaks 

 of certain tracts of water in the middle of each of the basins, where 

 the fluid remains motionless, and where no current exists, shown in 

 the chart by the absence of the arrows marking the direction of cur- 

 rents. Similar but much simpler operations are going on in the at- 

 mosphere, producing trade-winds and their counter currents, the 

 cause of which has long been known, and M. Babinet has been led 

 through them to the present solution of the oceanic current phenom- 

 ena. This double circulation of air and water possesses great influ- 

 ence in the mitigation of the climate, and the consequences would be 

 inconceivable, if, as in the Ptolemaic system, the earth were to stand 

 still, and the sun to revolve round her, for the revolution of the 

 earth on her own axis, and round the sun, is one of the most important 

 elements in the terrestrial system. 



THE WATER-THERMOMETER. 



LIEUT. MAURY states that he has been very much assisted in de- 

 veloping his theory of winds and currents by means of the thermom- 

 eter used by some vessels for determining the temperature of the 

 water. It was by means of these observations on the temperature 

 of the water that he was enabled to prove that off" the shores of 

 South America, between the parallels of 35 and 40 S., there is a 

 region of the ocean in which the temperature is as high as that of 

 our own Gulf Stream, while in the middle of the ocean and between 

 the same parallels the temperature of the water is not so great by 

 22. Now this very region is noted for its gales, being the most 

 stormy that the as yet incomplete charts of the South Atlantic indi- 

 cate. Lieut. Maury says, however, that very few navigators make 

 use of the water-thermometer, so that he has experienced some in- 

 convenience in his undertaking. He is the more surprised at this, 

 from the fact that New York owes much of her commercial impor- 

 tance to a discovery that was made by this thermometer. At the 

 time when Dr. Franklin discovered the Gulf Stream, Charleston 

 had more foreign trade than New York and all the New England 

 States together. Charleston was then the half-way house between 

 New and Old England. When a vessel in attempting to enter the 

 Delaware or Sandy Hook met a northwest gale or snow-storm, as at 

 certain seasons she is apt to do, instead of running off for a few hours 

 into the Gulf Stream to thaw and get warm, as she now does, she 

 used to put off for Charleston or the West Indies, and there remain- 

 ed till the return of spring before making another attempt. A beau- 

 tiful instance this of the importance and bearings of a single fact, 

 elicited by science from the works of nature. 



