88 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS METEOFwOLOGY. 



good and wholesome in its influences, and the contemplation of 

 it well calculated to excite in the bosom of right-minded philoso- 

 phers the deepest and best of emotions. 



238. Upon the proper adjustments of the djaiamical forces 

 How supplies of fresh -which keep up thoso ccascless movements the life of 



air are brought down . ^. ^ -, -, t/- j^i • ji j. • i xi n 



from the upper sky. orgauic naturc depeuds. 11 the air that is breathed 

 were not taken away and renewed, warm-blooded life would cease ; 

 if carbon, and oxygen, and hydrogen, and water were not in due 

 quantities dispensed by the restless au' to the flora of the earth, all 

 vegetation would perish for lack of food. That our planet may be 

 liable to no such calamity, power has been given to the wayward 

 wind, as it " bloweth where it listeth," to bring do^\ii from the 

 pui'e blue sky fi'esh supplies of life-giving air wherever it is 

 wanted, and to catch up li^om the earth wherever it may be found, 

 that which has become stale — to force it up, there to be deflagrated 

 among the clouds, pmified and. renovated by processes known 

 only to Him whose ministers they are. The slightest change 

 in the puiity of the atmosphere, though it may be too slight for 

 recognition by chemical analysis in the laboratory, is sure to be 

 detected by its effects upon the nicer chemistry of the human 

 system, for it is known to be productive of disease and death. 

 No chemical tests are sensitive enough to tell us what those 

 changes are, but experience has taught us the necessity of ventila- 

 tion in om' buildings, of circulation through om* groves. The 

 cry in cities for fresh air from the mountains or the sea, reminds 

 us continually of the life-giving virtues of circulation. Experience 

 teaches that all air when pent up and deprived of circulation be- 

 comes impm-e and poisonous. 



239. How minute, then, pervading, and general, benignant, 

 Beautiful and benign sm'c, and pcrfcct uiust bc that system of circulation 

 arrangements. which iuvosts the atmosplierc and makes " the whole 

 world kin ?" In the system of vertical circulation which I have 

 been endeavoming to describe, we see, as in a figure, the lither sky 

 filled with crystal vessels full of life-giving air continually ascend- 

 ing and descending between the bottom and the top of the atmo- 

 spherical ocean ; these buckets are let down by invisible hands fi'om 

 above, and, as they are taken up again, they carry off from the 

 smface, to be pmified in the laboratory of the skies, phials of 

 mephitic vapom^s and noxious gases, Avith the dank and deadly air 

 i)f marshes, ponds, and rivers. 



240. Whenever, by study and research, we succeed in gaining 



