Astronomers Who Have Lately Been Directing Minute Attention To Falling-Stars And Their Parallaxes, Consider Them As Meteors Belonging To

The farthest limits of our atmosphere, between the region of the Aurora Borealis and that of the lightest clouds.* (* According

To the observations which I made on the ridge of the Andes, at an elevation of 2700 toises, on the moutons, or little white fleecy clouds, it appeared to me, that their elevation is sometimes not less than 6000 toises above the level of the coast.) Some have been seen, which had not more than 14,000 toises, or about five leagues of elevation. The highest do not appear to exceed thirty leagues. They are often more than a hundred feet in diameter: and their swiftness is such, that they dart in a few seconds through a space of two leagues. Of some which have been measured, the direction was almost perpendicularly upward, or forming an angle of 50 degrees with the vertical line. This extremely remarkable circumstance has led to the conclusion, that falling-stars are not aerolites which, after having hovered a long time in space, unite on accidentally entering into our atmosphere, and fall towards the earth.* (* M. Chladni, who at first considered falling-stars to be aerolites, subsequently abandoned that idea.)

Whatever may be the origin of these luminous meteors, it is difficult to conceive an instantaneous inflammation taking place in a region where there is less air than in the vacuum of our air-pumps; and where (at the height of 25,000 toises) the mercury in the barometer would not rise to 0.012 of a line.

Enter page number Go  Previous Next
Page 559 of 779
Words from 152087 to 152359 of 211363