CLIMATOLOGY. 32o 



under the name of Hippalos. In the knowledge of the mon- 

 soons, which undoubtedly dates back thousands of years 

 amongst the inhabitants of Hindostan and China, of the 

 eastern parts of the Arabian Gulf and of the western shores 

 of the Malayan Sea, and in the still more ancient and more 

 general acquaintance with land and sea winds, lies concealed, 

 as it were, the germ of that meteorological science, which is 

 now making such rapid progress. The long chain of magnetic 

 stations extending from Moscow to Pekin, across the whole of 

 Northern Asia, will prove of immense importance in deter- 

 mining the law of the winds, since these stations kave also, for 

 their object, the investigation of general meteorological rela- 

 tions. The comparison of observations made at places lying 

 so many hundred miles apart, will decide, for instance, whe- 

 ther the same east wind blows from the elevated desert of 

 Gobi to the interior of Russia, or whether the direction of the 

 aerial current first began in the middle of the series of the 

 stations, by the descent of the air from the higher regions. 

 By means of such observations we may learn, in the strictest 

 sense, whence the wind cometh. If we only take the results on 

 which we may depend from those places, in which the obser- 

 vations on the direction of the winds have been continued 

 more than twenty years, we shall find, (from the most recent 

 and careful calculations of Wilhelm Mahlmann,) that in the 

 middle latitudes of the temperate zone, in both continents, 

 the prevailing aerial current has a west-south-west direction. 



Our insight into the distribution of heat in the atmosphere 

 has been rendered more clear since the attempt has been made 

 to connect together by lines those places, where the mean 

 annual summer and winter temperatures have been ascertained 

 by correct observations. The system of isothermal, isotheral, 

 and isochimenal lines, which I first brought into use in 1817, 

 may, perhaps, if it be gradually perfected by the united 

 efforts of investigators, serve as one of the main foundations 

 of comparative climatology. Terrestrial magnetism did not 

 acquire a right to be regarded as a science, until partial results 

 were graphically connected in a system of lines of equal dedi- 

 f.-*tion, equal inclination, and equal intensity. 



The term climate, taken in its most general sense, indicates 

 all the changes in the atmosphere, which sensibly affect our 

 organs, as temperature, humidity, variations in the barorne- 



T2 



