Page:Popular Science Monthly Volume 3.djvu/84

74 two more, while at Hanover he could only perceive the three brightest of them. The power of the telescope was correspondingly increased, so that an instrument of 9-4/10 inches of aperture was as effective as one with 12 inches at the sea-level. Some views of Saturn were exquisitely beautiful. The inner satellites, the details and markings of the rings, especially a dark stripe upon the outer ring, were clearly seen under powers ranging from 500 to 1,200. Besides the increase of the range of the instrument, the air was vastly more steady, and faint objects much more clearly defined.

The advantage was still greater in the careful spectroscopic observations that were made. Prof. Young had drawn up at Hanover a catalogue of 103 bright lines in the spectrum of the chromosphere; at Sherman the number was extended to 273, while, at moments of unusual solar disturbance, there were glimpses of at least as many more. Sulphur, strontium, and cerium, are almost certainly proved to be constituents of the solar atmosphere, and zinc, erbium, and didymium are strongly indicated. It was hoped that at the base of the chromosphere there might be seen the reversal of the dark lines of the spectrum, which is so wondrously beautiful at the commencement and close of a total solar eclipse. But in this hope the observers were disappointed; the appearance, at the distance of 1" or 15" from the edge of the photosphere, giving a spectrum principally continuous, most of the. dark lines vanishing or being much weakened. This result confirms the observations of Secchi, who reports at the edge of the sun a layer giving a continuous spectrum.

Curious observations were made upon the spectra of sun-spots, and a catalogue was made of 155 lines more or less affected, either greatly widened or weakened, or reversed. A number of bright lines were found in the spectrum of the nucleus, and some peculiarly shaded, as if they were the product of a combination of elements which, from the reduced temperature over the spots, had been able to exercise their chemical affinities.

Many solar eruptions were watched moving with velocities varying from 150 to 250 miles per second, and pouring forth their whirlwinds and torrents of ejected gas through the molten atmosphere. The most interesting eruption was visible on the surface of the sun itself in the vicinity of a large spot.

The magnetic observations were as satisfactory as any that were made, and yet prove that, although our greatest magnetic storms are only remotely connected with solar influence, every solar paroxysm has a direct and immediate effect upon terrestrial magnetism. On the 3d and 5th of August there were violent paroxysms of solar eruption. At just the minute these eruptions took place, the record of the vertical Magnetic Force shows marked and sudden magnetic impulses, a peculiar shuddering of the magnetic needle for that very time. The photographic copies of the vertical Force Curve at Greenwich and