ORGANIC I/IFE. 347 



out all the aerial strata from the place of observation to the 

 extremest confines of the atmosphere, whilst* the thermometer 

 and psychrometer only acquaint us with all the variations 

 occurring in the local heat and moisture of the lower strata of 

 air in contact with the ground. The simultaneous thermic and 

 hygromctric modifications of the upper regions of the air, can 

 only be learnt (when direct observations on mountain stations or 

 aerostatic ascents are impracticable,) from hypothetical combi- 

 nations, by making the barometer serve both as a thermometer 

 and an hygrometer. Important changes of weather are not 

 owir.g to merely local causes, situated at the place of observa- 

 tion, but are the consequence of a disturbance in the equili- 

 brium of the aerial currents at a great distance from the surface 

 of the Earth, in the higher strata of the atmosphere, bringing 

 cold or warm, dry or moist air, rendering the sky cloudy or 

 serene, and converting the accumulated masses of clouds into 

 light feathery cirri. As therefore the inaccessibility of the 

 phenomenon is added to the manifold nature and complication 

 of the disturbances, it has always appeared to me, that mete- 

 orology must first seek its foundation and progress in the 

 torrid zone, where the variations of the atmospheric pressure, 

 the course of hydro-meteors, and the phenomena of electric 

 explosion, are all of periodic occurrence. 



As we have now passed in review the whole sphere of 

 inorganic terrestrial life, and have briefly considered our 

 planet with reference to its form, its internal heat, its electro- 

 magnetic tension, its phenomena of polar light, the volcanic 

 reaction of its interior on its variously composed solid crust, 

 and, lastly, the phenomena of its twofold envelopes the 

 aerial and liquid ocean we might, in accordance with the 

 older method of treating physical geography, consider that we 

 had completed our descriptive history of the globe. But the 

 nobler aim I have proposed to myself, of raising the contempla- 

 tion of nature to a more elevated point of view, would be 

 defeated, and this delineation of nature would appear to lose 

 its most attractive charm, if it did not also include the sphere 

 of organic life, in the many stages of its typical development. 



* Kamtz, in Schumacher's Jahrbuch fur 1838, s. 285. Regarding 

 the opposite distribution of heat in the east and the west of Europe and 

 North America, see Dove, Itepertorium der Physik, bd. iii. s. 392- 

 396. 



