276 CHEMISTRY. 



which he said this is thus related : Mr. Stephenson asked 

 the late Dean Buckland, " Can you tell me what is the 

 power that is driving that train ?" alluding to a train which 

 happened to be passing at the moment. The learned dean 

 answered, "I suppose it is one of your big engines." "But 

 what drives the engine?" "Oh, very likely a canny New- 

 castle driver." "What do you say to the light of the 

 sun ?" " How can that be ?" asked Buckland." It is noth- 

 ing else," said Stephenson. " It is light bottled up for tens 

 of thousands of years ; light absorbed by plants and veg- 

 etables, being necessary for the condensation of carbon dur- 

 ing the process of their growth, if it be not carbon in an- 

 other form ; and now, after being buried in the earth for 

 long ages in fields of coal, that latent light is again brought 

 forth and liberated, made to work as in that locomotive 

 for great human purposes." 



392. Chemical Influence of Light on Animals. The influ- 

 ence of light upon color is very much the same in animals 

 as in vegetables. Accordingly, the plumage of birds in 

 tropical climates presents the richest hues, while the pre- 

 vailing color in the colder regions is a russet brown. So, 

 also, those fishes that swim near the surface have various 

 and rich colors, while those that live in deep water are 

 gray or brown or black. Those that live at so great a 

 depth that very little light reaches them are nearly color- 

 less. It is pretty well ascertained that at depths where no 

 light can penetrate there are no fishes or other animals of 

 a high order, showing how dependent animal life is upon 

 light. The influence of light upon life and health has at- 

 tracted considerable attention of late ; and, although some 

 extravagant things have been said about it by superficial 

 enthusiasts, there is no doubt that it is an influence which 

 should be seriously taken into the account in the arrange- 

 ment of our houses and workshops, and in the formation 

 of our habits of living. 



