468 THE POPULAR SCIENCE MONTHLY. 



far below the dew-point, very little dew was deposited. The air was 

 obviously a dry air. The sky was perfectly cloudless, while the barely 

 perceptible movement of the air was from the northeast. At 10 p. m. 

 the temperature of the air-thermometer was 37, that of the wool-ther- 

 mometer being 20, a refrigeration of 17 being, therefore, observed 

 on this occasion. 



From the behavior of a smooth ball when urged in succession over 

 short grass, over a gravel- walk, over a boarded floor, and over ice, it 

 has been inferred that, were friction entirely withdrawn, we should 

 have no retardation. In a similar way, when, under atmospheric condi- 

 tions visibly the same, we observe that the refrigeration of the earth's 

 surface at night markedly increases with the dryness of the atmosphere, 

 we may infer what would occur if the invisible atmospheric vapor 

 were entirely withdrawn. I am far from saying that the body of the 

 atmosphere exerts no action whatever upon the waves of terrestrial 

 heat ; but only that its action is so small that, when due precautions 

 are taken to have the air pure and dry, laboratory experiments fail to 

 reveal any action. Without its vaporous screen, our solid earth would 

 practically be in the presence of stellar space ; and with that space, so 

 long as a difference existed between them, the earth would continue 

 to exchange temperatures. The final result of such a process may be 

 surmised. If carried far enough, it would infallibly extinguish the 

 life of our planet. Contemporary Review. 



-- 



THE LITTLE MISSOURI BAD LANDS. 



By Professor T. H. McBRIDE. 



"All things are engaged in writing their history. The planet, the pebble goes at- 

 tended by its shadow. The rolling stone leaves its scratches on the mountain ; the 

 river its channel in the soil. . . . The falling drop makes its sculpture in the sand or 

 stone." Emerson. 



BAD Lands, so called, occur in various parts of the wide plateaus 

 adjacent to the Rocky Mountains. There are Bad Lands in 

 Kansas, Bad Lands in Nebraska, in Dakota, and in the Territories far- 

 ther west. The English name, probably because of intelligibility and 

 brevity, seems about to supplant the old French Mauvaises Terres by 

 which early travelers were wont to describe these remarkable regions. 

 Either appellation is appropriate, for these lands, at ordinary estimate, 

 are in many places nearly valueless, and yet the voyageur meant by 

 his mauvaises probably nothing more than that the country was diffi- 

 cult of transit terres mauvaises a traverser. However this may be, 



