Page:Popular Science Monthly Volume 58.djvu/327

Rh From what has been said the question which will first occupy our attention is that of the distribution of the stars with reference to the galactic plane, or rather, the great circle forming the central line of the Milky Way.

The whole sky is divided by Seeliger into nine zones or regions, each 20° in breadth, by small circles parallel to the galactic circle. Region I. is a circle of 20° radius, whose center is the galactic pole. Round this central circle is a zone 20° in breadth, called Zone II. Continuing the division, it will be seen that Zone V. is the central one of the Milky Way, extending 10° on each side of the galactic circle.

The condensed result of the work is shown in the following table:

Column 'Area' shows the number of square degrees in each region, so far as included in the survey. It will be remarked that the catalogues in question do not include the whole sky, as they stop at 24° S. Dec.

Column 'Stars' shows the number of stars to magnitude 9.0 found in each area.

Column 'Density' is the quotient of the number of stars by the area, and is, therefore, the mean number of stars per square degree in each region. In column 'D' these numbers are corrected, for certain anomalies in the magnitudes given by the catalogues, so as to reduce them to a common standard.

A study of the last two columns is decisive of one of the fundamental questions already raised. The star density in the several regions increases continuously from each pole (regions I. and V.) to the galaxy itself. If the latter were a simple ring of stars surrounding a spherical system of stars, the star density would be about the same in regions I., II. and III., and also in VII., VIII. and IX., but would suddenly increase in IV. and VI. as the boundary of the ring was approached. Instead of such being the case, the numbers 2.78, 3.03 and 3.54 in the north, and 3.14, 3.21 and 3.71 in the south, show a progressive increase from the galactic pole to the galaxy itself.

The conclusion to be drawn is a fundamental one. The universe, or, at least, the denser portions of it, is really flattened between the