14 THE PHYSICAL GEOGRAPHY OF THE SEA. 



US the aurora of the morning and twilight of evening; it disperses 

 and refracts their various tints to beautify the approach and the 

 retreat of the orb of day. But for the atmosphere, sunshine would 

 burst on us in a moment and fail us in the twinkling of an eye, 

 removing us in an instant from midnight darkness to the blaze 

 of noon. We should have no twilight to Boften and beautify the 

 landscape, no clouds to shade us from the scorching heat ; but the 

 bald earth, as it revolved on its axis, would turn its tanned and 

 weakened front to the full and unmitigated rays of the lord of 

 day. 



89. " The atmosphere affords the gas which vivifies and warms 

 Its functions, our framcs ; it receives into itself that which has 

 been polluted by use, and is thrown off as noxious. It feeds the 

 flame of life exactly as it does that of the fire. It is in both cases 

 consumed, in both cases it affords the food of consumption, and 

 in both cases it becomes combined with charcoal, which requires 

 it for combustion, and which removes it when combustion is over. 

 It is the girdling encircling air that makes the whole world kin. 

 The carbonic acid with which to-day our breathing fills the air, 

 to-morrow seeks its way round the world. The date-trees that 

 grow round the falls of the Mle will drink it in by their leaves ; 

 the cedars of Lebanon will take of it to add to their stature ; the 

 cocoa-nuts of Tahiti will grow rapidly upon it; and the palms 

 and bananas of Japan will change it into flowers. The oxygen 

 we are breathing was distilled for us some short time ago by the 

 magnolias of the Susquehanna and the great trees that skirt the 

 Orinoco and the Amazon ; the giant rhododendrons of the Hima- 

 layas contributed to it, and the roses and myrtles of Cashmere, 

 the cinnamon-tree of Ceylon, and the forest, older than the flood, 

 that lies buried deep in the heart of Africa, far behind the Mount- 

 ains of the Moon, gave it out. The rain we see descending was 

 thawed for us out of the icebergs which have watched the Polar 

 Star for ages, or it came from snows that rested on the summits 

 of the Alps, but which the lotus lilies have soaked up from the 

 Nile, and exhaled as vapor again into the ever-present air." 



40. There are processes no less interesting going on in other 

 The operations of p^rts of this magnificent field of research. Water 

 ^^*^^- is nature's carrier. With its currents it conveys 



heat away from the torrid zone and ice from the frigid ; or, bot- 



