Page:Popular Science Monthly Volume 24.djvu/499

Rh of its own circuit. Nearly every night after the installation of the apparatus, a yellow-white light illuminated the points without anything like it appearing on the heights in the neighborhood, while the needle of the galvanometer by its motions betrayed the passage of an electric current. The light was analyzed in the spectroscope, and gave the greenish-yellow ray that characterizes the aurora borealis. The



intensity of the glow and the deviations of the needle, moreover, varied continually. In the mean time the hoar-frost which was deposited on the wires quickly destroyed the insulation, and rendered an experiment of any duration almost impossible. The numbness of the fingers of the operators, induced by the cold, added to the difficulties of the study.

The apparatus afterward set up on Pietarintunturi, in more than 78° of latitude, was disposed in an almost identical manner, except that the surface furnished with points was a half less; but, M. Lenström remarks, the proximity to the "maximum zone" of auroras compensated for this inferiority. On the 29th of December an "auroral ray" made its appearance above the net, which it dominated vertically from a height of one hundred and twenty metres.

The difficulties of the question of the exact origin and nature of the auroral phenomena have not been solved yet; but we have good reason to believe that a long approach has been made in the recent experiments toward a solution, and grounds to believe that science will soon remove them all; and we shall no longer be able to repeat what Haüy, less than a hundred years ago, said on the same subject, "It is not always what has been known longest that is best."—Translated for the Popular Science Monthly from the Revue des Deux Mondes.