* NATURAL THEOLOGY. 



effect the separation which we wish, by any art 

 or means whatever. 



By evaporation, water is carried up into the 

 air ; by the converse of evaporation, it falls down 

 upon the earth. And how does it fall ? Not by 

 the clouds being all at once re-converted into wa- 

 ter, and descending like a sheet ; not in rushing 

 down in columns from a spout ; but in moderate 

 drops, as from a colander. Our watering-pots are 

 made to imitate showers of rain. Yet, a priori, 

 I should have thought either of the two former 

 methods more likely to have taken place than the 

 last. 



By respiration, flame, putrefaction, air is ren- 

 dered unfit for the support of animal life. By the 

 constant operation of these corrupting principles, 

 the whole atmosphere, if there were no restoring 

 causes, would come at length to be deprived of its 

 necessary degree of purity. Some of these causes 

 seem to have been discovered, and their efficacy 

 ascertained by experiment ; and so far as the dis- 

 covery has proceeded, it opens to us a beautiful 

 and a wonderful economy. Vegetation proves to 

 be one of them. A sprig of mint, corked up with 

 a small portion of foul air, placed in the light, ren- 

 ders it again capable of supporting light or flame. 

 Here, therefore, is a constant circulation of bene- 

 fits maintained between the two great provinces 

 of organized nature. The plant purifies what the 

 animal has poisoned ; in return, the contaminated 



