In some notes on photographs of the Milky Way, Prof. Barnard says with reference to the great nebula near ρ Ophiuchi, “The peculiarity of this region has suggested to me the idea that the apparently small stars forming the ground work of the Milky Way here, are really very small bodies compared with our own sun”; and again, referring to the region near β Cygni, “One is specially struck with the apparent extreme smallness of the general mass of the stars in this region.” Again, with reference to χ Cygni, he says, “The stars here also are remarkably uniform in size.”[459]
Eastman’s results for parallax seem to show that “the fainter rather than the brighter stars are nearest to our system.” But this apparent paradox is considered by Mr. Monck to be very misleading;[460] and the present writer holds the same opinion.
Prof. Kapteyn finds “that stars whose proper motions exceed 0″·05 are not more numerous in the Milky Way than in other parts of the sky; or, in other words, if only the stars having proper motions of 0″·05 or upwards were mapped, there would be no aggregation of stars showing the existence of the Milky Way.”[461]
With reference to the number of stars visible on photographs, the late Dr. Isaac Roberts says—
“So far as I am able at present to judge, under the atmospheric conditions prevalent in this country, the limit of the photographic method of delineation will be reached at stellar, or nebular, light of the feebleness of about 18th-magnitude stars. The reason for this inference is that the general illumination of the atmosphere by starlight concentrated upon a film by the instrument will mask the light of objects that are fainter than about 18th-magnitude stars.”[462]
With reference to blank spaces in the sky, the late Mr. Norman Pogson remarked—
“Near S Ophiuchi we find one of the most remarkable vacuities in this hemisphere—an elliptic space of about 65′ in length in the direction of R.A., and 40′ in width, in which there exists no star larger than the 13th magnitude ... it is impossible to turn a large telescope in that direction and, if I may so express it, view such black darkness, without a feeling that we are here searching into the remote regions of space, far beyond the limits of our own sidereal system.”[463]
Prof. Barnard describes some regions in the constellation Taurus containing “dark lanes” in a groundwork of faint nebulosity. He gives two beautiful photographs of the regions referred to, and says that the dark holes and lanes are apparently darker than the sky in the immediate vicinity. He says, “A very singular feature in this connection is that the stars also are absent in general from the lanes.” A close examination of these photographs has given the present writer the impression that the dark lanes and spots are in the nebulosity, and that the nebulosity is mixed up with the stars. This would account for the fact that the stars are in general absent from the dark lanes. For if there is an intimate relation between the stars and the nebulosity, it would follow that where there is no nebulosity in this particular region there would be no stars. Prof. Barnard adds that the nebulosity is easily visible in a 12-inch telescope.[464]
With reference to the life of the universe, Prof. F. R. Moulton well says—
“The lifetime of a man seems fairly long, and the epoch when Troy was besieged, or when the Pharaohs piled up the pyramids in the valley of the Nile, or when our ancestors separated on the high plateaux of Asia, seems extremely remote, but these intervals are only moments compared to the immense periods required for geological evolutions and the enormously greater ones consumed in the developement of worlds from widely extended nebulous masses. We recognize the existence of only those forces whose immediate consequences are appreciable, and it may be that those whose effects are yet unseen are really of the highest importance. A little creature whose life extended over only two or three hours of a summer’s day might be led, if he were sufficiently endowed with intelligence, to infer that passing clouds were the chief influence at work in changing the climate instead of perceiving that the sun’s slow motion across the sky would bring on the night and its southward motion the winter.”[465]