1851.] 



HOPKINS ON CHANGES OF CLIMATE. 



n 



of the Falkland Islands in 50° S. latitude. But there are only a 

 few observations recorded either of the January or the July tempe- 

 ratures along that southern parallel. 



There is, on the contrary, a striking contrast between the north- 

 ern and southern hemispheres with respect to the differences of sum- 

 mer and winter temperatures. These differences are in all cases 

 considerably greater, and in the higher latitudes much greater, in the 

 northern than in the southern hemisphere. 



From these results it would appear, that the greater or less extent 

 of land or sea has very little effect on the mean annual temperature of an 

 entire parallel of latitudes from the equator to about 45° of latitude ; 

 and that beyond that parallel the predominance of land diminishes, 

 while that of sea increases the mean annual temperature. Also, that a 

 predominance of sea, in all cases, but especially in the higher latitudes, 

 produces a greater equality of summer and winter temperatures. 



18. Again, let us compare the temperatures of different stations 

 along the same parallel of latitude, some of these stations being cen- 

 trally situated as regards the continents, and others as regards the 

 sea. It should here be remarked that the temperatures of the stations 

 in the Atlantic for the 40th and 50th degrees of latitude must be re- 

 garded as partly hypothetical, because I have estimated them inde- 

 pendently of the influence of the Gulf-stream. The following table 

 embodies the results, deduced from Dove's map, for different stations 

 on six parallels from that of 20° S. lat. to that of 50° N. lat. inclusive. 



Parallel of 

 Latitude. 



20° S. 



10° S. 



Longitude. 



23 E. Land 



20 W. Sea... 



56 W. Land 



140 W. Sea... 



20° N... 



30°N.... 



23 E. Land 



20 W. Sea... 



56 W. Land 



HOW. Sea... 



Temperature. 



January. 



30 E. Land ... 



40 W. Sea 



150 W. Sea 



30 E. Land 



40 W. Sea.. 



150 W. Sea.. 



40° N. 



50° N. 



48 E. Land 

 40 W. Sea... 

 90 W. Land 

 170 W. Sea... 



80 E. Land 



30 W. Sea... 



90 W. Land 



150 W. Sea... 



78 F. 

 74-5 



78 



77 



78 

 77 

 78 

 78 



65 

 71 

 71 



56 

 59 

 62 



32 

 44 

 31 

 54 





 26 





 35 



July. 



71 F. 



67 

 68 



74 



75 



74 

 75 



77 



91 

 76 



78-5 



81-5 



73 



72-5 



79 

 68 

 75 

 59 



71 

 61 

 61 

 53 



Diflfer- 

 ence. 



7F. 

 7-5 

 10 

 3 



3 

 3 

 3 



1 



26 

 5 

 7-5 



Mean. 



25-5 



68-75 ] 



14 



66-25 \ 



10-5 



67-25 J 



47 



55-5 1 



24 



56 1 



44 



53 • 



5 



56-5 J 



71 



35-5 1 



35 



43-5 



61 



30-5 ■ 



18 



44 J 



