18 COSMOS. 



they photometrically belong. If we limit our attention to tlio 

 bright stars of the first three or four classes of magni- 

 tudes, we shall find them distributed on the whole with 

 tolerable uniformity, 68 although in the southern hemisphere, 

 from e Orionis to a Crucis, they are locally crowded together 

 in a splendid zone in the direction of a great circle. The 

 various opinions expressed by different travellers on the 

 relative beauty of the northern and southern hemispheres, 

 frequently, I believe, depends wholly on the circumstance, 

 that some of these observers have visited the southern regions 

 at a period of the year when the finest portion of the con- 

 stellations culminate in the day-time. It follows, from the 

 gaugings of the two Herschels in the northern and southern 

 hemispheres, that the fixed stars from the 5th and 6th to the 

 10th and 15th magnitudes (particularly, therefore, telescopic 

 stars) increase regularly in density as we approach the 

 galactic circle (6 yaXa^ias KVK\OS) ; and that there are therefore 

 poles rich in stars, and others poor in stars, the latter being 

 at right angles to the principal axis of the Milky Way. The 

 density of the stellar light is at its minimum at the poles of 

 the galactic circle ; and it increases in all directions, at first 

 slowly, and then rapidly, in proportion to the increased 

 galactic polar distance. 



By an ingenious and careful consideration of the results of 

 the gauges already made, Struve found that on the average 

 there, are 29-4 times (nearly 30 times) as many stars in the 

 centre of the Milky Way as in regions surrounding the 

 galactic poles. In northern galactic polar distances of 

 0, 30, 60, 75, and 90, the relative numbers of the stars 

 in a telescopic field of vision of 15' diameter, are 4-15, 6'52, 

 17-68, 30-30, and 122-00. Notwithstanding the great simi- 

 larity in the law of increase in the abundance of the stars, we 



68 Outlines of Astr., 785. 



