1 THE HARMONIES OF NATURE. 



earth, and pours floods of warmth into the bosom of the ocean, 

 the rarefied air, as if attracted by the great luminary, ascends in 

 vertical columns to the skies. But as the law of gravity tolerates 

 no void, cold air columns keep constantly rushing in from the 

 poles to replace the ascending equatorial air-currents, which, 

 on reaching the higher regions of the atmosphere, in their turn 

 gradually descend towards the poles, where, condensed by the 

 cold, they again resume their equatorial migrations. 



While the sun thus perpetually ventilates the air on a truly 

 magnificent scale, the unequal warmth of the various bodies 

 which clothe the surface of the earth likewise causes a constant 

 agitation of the atmosphere. Grass, stones, the leaves of the 

 forest, the waters, are all unequally heated by the sun, radiate 

 with unequal power the caloric they have absorbed, communicate 

 to the contiguous air a higher or a lower temperature, and con- 

 sequently a diminution or an increase of weight. But the air 

 constantly strives to restore its equilibrium, and thus sweeps 

 along in constantly renewed currents over the surface of the 

 bodies which cause these constant perturbations. 



The carbonic acid which we exhale with our warm breath is 

 carried to a distance before our breast expands for a new inspi- 

 ration, and, in the open air, not a single atom that has ever es- 

 caped our lungs will again return into their cells. Thus the sun, 

 the source of light and warmth, is also one of the chief pro- 

 moters of our health. 



The organisation of all plants and animals is so intimately 

 based upon the existing composition of the atmosphere, that, 

 supposing a change to take place in the constitution of the air, 

 all beings actually existing must necessarily perish. If the 

 atmosphere contained a greater proportion of oxygen, the 

 current of our life would be accelerated for a time, but would 

 also be much more rapidly consumed ; and if, on the other hand, 

 its quantity was considerably reduced, the respiratory process 

 would languish, and life soon become extinct. 



The petrified remains of birds and quadrupeds which we find 

 in the deposits of the primeval ocean prove that during an in- 

 calculable series of ages the composition of the atmosphere 

 cannot have differed in any notable degree from its present 

 condition, but they prove at the same time how perfect the 

 laws must be, which during such vast periods have constantly 

 maintained its uniformity. 



