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CHAP. XV. THE GENERAL DISTRIBUTION OF STARS. 



THE labours of three or four generations of astronomers have con- 

 clusively proved that the distribution of the stars well within our ken 

 is dominated by the Milky Way. Although the Milky Way to the 

 naked eye looks very unlike the other parts of the heavens, we have 

 known since the time of Galileo that the difference arises from the fact 

 that it is composed of a tremendous multitude of stars, a very large 

 percentage of the masses of matter which compose our system lying in 

 its plane ; it does not merely represent a fiery or igneous fluid, as dif- 

 ferent schools thought it did in the olden days. A small opera-glass 

 or telescope easily shows us that we are in presence of an innumerable 

 multitude of stars. 



The Milky Way is a great circle inclined at an angle of about 62 

 to the earth's equator or to the equatorial plane extending to the stars. 

 "V\'e know nothing, of course, of the reason for that angle of 62, but 

 it has its importance, because not only must the belt cross the equator 

 at two opposite points, as it does in two opposite constellations, Aquila 

 and Monoceros, but the poles of the Milky Way must lie at the points 

 of greatest distance from the junction with the equator in certain 

 constellations. These are Coma Berenices and Sculptor, and the posi- 

 tion of the N. galactic pole, as the north pole of the Milky Way is 

 called, is in R.A. 12 h. 40 m. Dec. + 28. 



When we come to look at the Milky Way a little more closely, we 

 find that from two points in it branches are thrown out, so that over 

 some part of its orbit, so to speak, it is double. The great rift which 

 separates these two parts of it begins near a star in the southern 

 hemisphere, a Centauri, and it continues for more than six hours in 

 right ascension until the two branches meet again in the constella- 

 tion Cygnus, which is well within our ken in the northern heavens. 

 The distance apart of the middle lines of these two components of the 

 Milky Way. where the split is most obvious, is something like 17, so 

 that, in addition to the angle of 62 from the ecliptic, in some part of 

 the Milky Way, there is another offshoot springing out of it at an 

 angle of something like 17. The regions of greater brilliancy corre- 

 spond approximately to the places where the branches intersect each 

 other. In short, there are sundry indications that the whole pheno- 

 mena of the Milky Way may become simplified by treating it as the 



