CHEMISTRY OF SUNLIGHT. 55 



that may be another object accomplished, by 

 their different hues, but were all admirably 

 adapted in order to enable the flowers to drink in 

 that portion of the quickening influences, of the 

 sun's rays, which is most expedient for their 

 peculiar wants. 



The heat of the sun's rays performs other 

 duties of a more momentous kind than any 

 hitherto indicated. It is the grand agent by 

 which currents are produced in the air. Yet, 

 little do we think that the summer breeze that 

 fans our cheek, little does the sailor think that 

 the steady wind which impels his vessel, or the 

 storm which threatens him and his ship with 

 destruction, are alike put into movement by 

 the subtile beams of the sun ! Thus the cir- 

 culation necessary for the preservation of the 

 purity of the atmosphere is sustained, thus 

 the clouds are wafted to drop their burden on 

 our thirsty fields, thus man can spread his 

 canvas wings, and fly to the ends of the earth 

 all as a consequence of this warm flood of 

 sunshine in which the insects bask, and the 

 landscape lies bathed and asleep. The heat of 

 the sun is the great cause of the evaporation of 

 water, and thus it lifts into the air the vapour, 

 which, when condensed, comes down as the 

 grateful shower to fertilize our land. Also, 

 since chemical changes of all kinds go on -much 



