58 



NATURE FOE ITS OWN SAKE 



of Scotland. In no warm country is there such 

 clear blue sky as one may see in the northwest 

 of America ; and if we may believe the descrip- 

 tions of Dr. Nansen, the Arctic explorer, this 

 blue grows more intense as we move toward the 

 poles, until at last it becomes of that violet hue 

 seen from mountain-peaks. The Egyptian blue 

 is often "deep" when the air is clear and 

 still, but with winds, heat and dryness it takes 

 on a warm tone as though it were seen through 

 a red dust - veil. A similar effect may be 

 noticed over cities like London, where smoke 

 and soot are continually fouling the air. The 

 blue has a suffusion of pink or copper-color that 

 gives it a hot look. In moist climates like Ger- 

 many or Holland, there are often very clear 

 skies, but the moisture particles in the air 

 usually tend toward the production of a pale, 

 milky whiteness in the blue. Again, in all 

 countries of the northern temperate zone the 

 purest summer skies are in the months of May 

 and June. After these months the hot and 

 dry summer begins to pale the blue, and in the 

 autumn, when the leaves are changing to gold 

 and scarlet, the sky in perfect harmony becomes 

 rosy and often opalescent. 

 If people are little observant of the blue sky 



