Evidence pointing the same way is afforded by circular apertures in the Galaxy, or indeed by apertures of other forms. Another peculiarity of these cavities is also noticeable; whereas on the borders of every one there are many lucid stars, or in some cases two or three very bright stars, within the cavity there is a marked paucity of stars. This phenomenon seems to indicate a much closer connection between the brighter stars and the milky light beyond than is supposed on the stratum theory. One can hardly conceive the phenomenon to be wholly accidental.
There are some other points on which I fain would dwell, but space will not permit me. I will merely note that there are peculiarities in the distribution of red double and multiple stars, in the position in which temporary stars have made their appearance, and in the distribution of nebulæ, which seem very worthy of notice.
One point, however, immediately connected with my subject remains to be mentioned. I have traced streams of stars more conspicuous than those forming the Milky Way. We have also evidence of streams of light yet more delicate and evanescent than the light of our own Galaxy. In Sir John Herschel’s great work on the southern skies, he notes the frequent recurrence of “an exceedingly delicate and uniform dotting, or stippling, of the field of view by points of light too small to admit of any one being steadily or fully examined, and too numerous for counting, were it possible so to view them.” In thirty-seven places he detected this remarkable and significant phenomenon; a phenomenon so faint that he says, “The idea of illusion has continually arisen subsequently”; an idea well befitting the modesty of the philosophic observer, but which those who appreciate Sir John Herschel’s skill as an observer will be very unwilling to accept. As Professor Nichol remarks, “It is enough to read from Herschel’s notebook—‘I feel satisfied the stippling is no illusion, for its dark mottling moves with the stars as I move the tube to and fro’—to feel convinced that the phenomenon is real.” Now a remarkable fact connected with those observations is, that when Sir J. Herschel marked down in a star-chart the places in which he had detected this nebulous appearance, he found that, “with the exception of three which appeared outlying and disconnected, they formed several distinct but continuous streams.”
FOOTNOTES:
[20] Field means the actual space covered by the lens.—E. S.
[21] Sometimes a singular regularity of curvature is noticed, and a spiral is formed closely resembling in configuration some of the great spiral nebulæ, as drawn by Lord Rosse, so that one is tempted to see in the centrifugal tendency of the disturbed water, and the centripetal effects caused by reflection from the basin’s surface, causes which may in some sense illustrate the laws operating in wider domains of space.
THE MAGELLANIC CLOUDS—ZODIACAL LIGHT—STAR GROUPS.—Amédée Guillemin
When we look on the region of the celestial vault which surrounds the South Pole, we can not help being struck with the contrast presented by the small quantity of stars which it contains, with the brilliant zone which borders the Milky Way, from Orion and Argo to the Centaur, passing by the Southern Cross. One solitary star of the first magnitude, Achernar, more distant from the pole than are the beautiful stars of the Centaur and of the Cross, shines in this part of the sky.
But even this circumstance renders the singular aspect of the two nebulous spots, which seem two detached pieces of the great galactic zone, still more striking. These half-stellar, half-nebulous systems, unequal in magnitude and brightness, but easily seen with the naked eye on a clear, moonless night, are situated, one, the larger and more brilliant, between the pole and Canopus, in the constellation of Doradus; the other, the smaller and less brilliant, ordinarily visible during the full moon, in Hydrus, between Achernar and the pole.