Page:Popular Science Monthly Volume 23.djvu/484

468 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 the temperature of the air-thermometer was 37°, that of the wool-thermometer 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short grass, over a gravel-walk, over a boarded floor, and over ice, it has been inferred that, were friction entirely withdrawn, we should have no retardation.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 conditions 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with the dryness of the atmosphere, we may infer what would occur if the invisible atmospheric vapor were entirely withdrawn.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.



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

AD 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 farther 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 difficult of transit—terres mauvaises à traverser. However this may be, 