CLIMATOLOGY. 227 



solid continental masses, as compared with the liquid oceanic. 

 These perturbations give rise to convex and concave summits 

 of the isothermal curves. There are, however, different 

 orders of disturbing causes, and each one must, therefore, be 

 considered separately, in order that their total effect may 

 afterwards be investigated with reference to the motion (direc- 

 tion, local curvature) of the isothermal lines, and the actions 

 by which they are connected together, modified, destroyed, or 

 increased in intensity, as manifested in the contact and inter- 

 section of small oscillatory movements. Such is the method 

 by which, I hope, it may some day be possible to connect 

 together, by empirical and numerically expressed laws, vast 

 series of apparently isolated facts, and to exhibit the mutual 

 dependence which must necessarily exist among them. 



The trade winds easterly winds blowing within the tro- 

 pics give rise, in both temperate zones, to the west, or west- 

 south-west winds which prevail in those regions, and which 

 are land winds to eastern coasts, and sea winds to western 

 coasts, extending over a space which, from the great mass and 

 the sinking of its cooled particles, is not capable of any con- 

 siderable degree of cooling, and hence it follows, that the east 

 winds of the Continent must be cooler than the west winds, 

 where their temperature is not affected by the occurrence of 

 oceanic currents near the shore. Cook's young companion on 

 his second voyage of circumnavigation, the intelligent George 

 Forster, to whom I am indebted for the lively interest which 

 prompted me to undertake distant travels, was the first who 

 drew attention, in a definite manner, to the climatic differ- 

 ences of temperature existing in the eastern and western 

 coasts of both continents, and to the similarity of temperature 

 of the western coast of North America in the middle lati- 

 tudes, with that of Western Europe.* Even in northern 

 latitudes exact observations show a striking difference between 

 the mean annual temperature of the east and west coasts of 

 America. The mean annual temperature of Nain, in Labrador, 

 flat 57 10') is fully 6 "8 below the freezing-point, whilst, on 

 the north-west coast, at New Archangel, in Russian America, 



* George Forster, Kleine Scfinften, th. iii. 1794, s. 87; Dove, la 

 Schumacher's Jahrbuch fur 1841. 8. 289 ; Kamtz, Meteordogie, bd. ii 

 i 41, 43, 67, and 96 ; Arago, in the Comptes rendus, t. i. p. 268. 



