346 COSMOS, 



tions in the elastic and electric tension, and in the hygrome- 

 tric condition of the vast aerial ocean, are all so intimately 

 connected together, that each individual meteorological process 

 is modified by the action of all the others. The complicated 

 nature of these disturbing causes (which involuntarily remind 

 us of those which the near and especially the smallest cosmical 

 bodies, the satellites, comets, and shooting stars, are subjected 

 in their course) increases the difficulty of giving a full explan- 

 ation of these involved meteorological phenomena ; and like- 

 wise limits, or wholly precludes the possibility of that 

 predetermination of atmospheric changes, which would be so 

 important for horticulture, agriculture, and navigation, no 

 less than for the comfort and enjoyment of life. Those who 

 place the value of meteorology in this problematic species of 

 prediction rather than in the knowledge of the phenomena 

 themselves, are firmly convinced that this branch of science, 

 on account of which so many expeditions to distant moun- 

 tainous regions have been undertaken, has not made any very 

 considerable progress for centuries past. The confidence 

 which they refuse to the physicist they yield to changes of 

 the moon, and to certain days marked in the calendar by the 

 superstition of a by-gone age. 



" Great local deviations from the distribution of the mean 

 temperature are of rare occurrence, the variations being in 

 general uniformly distributed over extensive tracts of land. 

 The deviation after attaining its maximum at a certain point, 

 gradually decreases to its limits ; when these are passed, how- 

 ever, decided deviations are observed in the opposite direction. 

 Similar relations of weather extend more frequently from south 

 to north, than from west to east. At the close of the year 1 829, 

 (when I had just completed my Siberian journey) the max- 

 imum of cold was at Berlin, whilst North America enjoyed 

 an unusually high temperature. It is an entirely arbitrary 

 assumption to believe that a hot summer succeeds a severe 

 winter, and that a cool summer is preceded by a mild winter." 

 Opposite relations of weather in contiguous countries, or in 

 two corn-growing continents, give rise to a beneficent equal- 

 ization in the prices of the products of the vine, and of agricul- 

 tural and horticultural cultivation. It has been justly 

 remarked, that it is the barometer alone which indicates to 

 us the changes that occur in the pressure of the air through- 



