82 THE WONDERFUL CENTURY. CHAP. ix. 



spot out of its direct rays would be completely dark, ex- 

 cept for light reflected from the walls. It would be 

 necessary to have windows all round and the walls all 

 white ; and 011 the north side of every house a high white 

 wall would have to be built to reflect the light and pre- 

 vent that side from being in total darkness. Even then 

 we should have to live in a perpetual glare, or shut out 

 the sun altogether and use artificial light as being a far 

 superior article. 



Much more important would be the effects of a dust- 

 free atmosphere in banishing clouds, or mist, or the 

 " gentle rain of heaven," and in giving us in their place 

 perpetual sunshine, desert lowlands, and mountains 

 devastated by unceasing floods and raging torrents, so as, 

 apparently, to render all life on the earth impossible. 



There are a few other phenomena, apparently due to 

 the same general causes, which may here be referred to. 

 Everyone must have noticed the difference in the atmos- 

 pheric effects and general character of the light in 

 spring and autumn, at times when the days are of the 

 same length, and consequently when the sun has the 

 same altitude at corresponding hours. In spring we 

 have a bluer sky and greater transparency of the atmos- 

 phere; in autumn, even on very fine days, there is 

 always a kind of yellowish haze, resulting in a want of 

 clearness in the air and purity of color in the sky. 

 These phenomena are quite intelligible when we con- 

 sider that during winter less dust is formed, and more is 

 brought down to the earth by rain and snow, resulting in 

 the transparent atmosphere of spring, while exactly 

 opposite conditions during summer bring about the mel- 

 low autumnal light. Again, the well-known beneficial 



