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observations of different ships at different seasons are collected, 

 should have their bounding lines of latitude and longitude brought 

 nearer together than may be required for the ocean at large. 



In looking forward to the results which are likely to be obtained 

 by the contemplated marine observations, it is reasonable that those 

 which may bear practically on the interests of navigation should 

 occupy the first place ; but, on the other hand, it would not be 

 easy to over-estimate the advantages to physical geography, of 

 general tables of the surface temperature of the ocean in the dif- 

 ferent months of the year, exhibiting, as they would do, its normal 

 and its abnormal states, the mean temperature of the different 

 parallels, and the deviations therefrom, whether permanent, peri- 

 odical, or occasional. The knowledge which such tables would 

 convey is essentially required for the study of climatology as a 

 science. 



The degree in which climatic variations extending over large 

 portions of the earth's surface may be influenced by the variable 

 phenomena of oceanic currents in different years, may perhaps be 

 illustrated by circumstances of known occurrence in the vicinity 

 of our own coasts. The admirable researches of Major Rennell 

 have shown that in ordinary years, the warm water of the great 

 current known by the name of the Gulf-stream is not found to the 

 east of the meridian of the Azores ; the sea being of ordinary ocean 

 temperature for its latitude at all seasons and in every direction, in 

 the great space comprised between the Azores, and the coasts of 

 Europe and North Africa : but Major Rennell has also shown that 

 on two occasions, viz. in 1776 and in 1821-1822, the warm water by 

 which the Gulf-stream is characterised throughout its whole course 

 (being several degrees above the ordinary ocean temperature in the 

 same latitude), was found to extend across this great expanse of 

 ocean, and in 1776 (in particular) was traced (by Dr. Franklin) 

 quite home to the coast of Europe. The presence of a body of 

 unusually heated water, extending for several hundred miles both in 

 latitude and in longitude, and continuing for several weeks, at a 

 season of the year when the prevailing winds blow from that quarter 

 on the coasts of England and France, can scarcely be imagined to 

 be without a considerable influence on the relations of temperature 

 and moisture in those countries. In accordance with this supposition, 



