32 PHYSICAL GEOGRAPHY. 



south, its distance from the sea, the constant motion of its atmos- 

 phere, the general character of its finely silicious soil and perfect 

 natural drainage, and its general freedom from swamps, bogs and 

 sloughs, all combine to give the State the purest possible atmos- 

 phere. Its constant breezes sweep away or mingle with the gen- 

 eral current of the atmosphere such impurities as may have been 

 generated from any cause. Only during the Indian summer of 

 autumn is there a haze that obscures distant objects. Fogs seldom 

 occur. It is remarkable at how great a distance' objects can usually 

 be seen. Often when a bluff is ascended the larger limbs of a tree 

 can be counted from eight to twelve miles distant. Objects univer- 

 sally appear to be much nearer than they really are, to strangers 

 coming from the East. I have sometimes been amused to see them 

 going through the same experience that befell me during my first 

 residence here the experience of shooting at prairie chickens 

 when they were a quarter of a mile off, under the supposition ^that 

 they were close by. Only gradually does the eye get accustomed 

 to measure distances in such a clear and rare atmosphere. In fact, 

 judging from the European meteorological reports, the atmosphere 

 of Nebraska is as clear, and much purer, than trje far-famed skies 

 of Italy and Greece. 



Owing to this pureness of the atmosphere, clouds, when formed, 

 are exceptionally clearly out lined. They stand out as most con- 

 spicuous objects in the sky. Nothing can surpass their evening or 

 morning splendors. The sunsets are remarkable for the brightness 

 and variety of their coloring. I have seen many magnificent sun- 

 sets in the mountains, but never anything to compare for extent, 

 coloring, form and grandeur, with those that so often occur on the 

 rolling prairies of Nebraska. 



Another prominent feature of the Nebraska atmosphere is the 

 allotropic form, called ozone, that oxygen so constantly assumes. 

 The amount of this in the atmosphere is very much greater than 

 in the East. During 1869 and 1870, while engaged almost con- 

 stantly in traveling and exploring over Northern Nebraska, I car- 

 ried with me much of the time the so-called Shoenbein test papers.* 

 These turned blue in a short time when exposed, thus indicating 

 the presence of ozone in the atmosphere. This rarely occurs in 

 the East, and even but slightly after a thunder-storm. Many other 



*Paper moistened with a solution of potassium iodide and starch, and kept until wanted for 

 use, in a tightly-stoppered bottle. 



