CHAPTERS ON THE STARS. 313 



fewest stars in the direction of the poles of the galaxy; and the number 

 in any given portion of the celestial sphere, say one square degree, 

 should continually increase, slowly at first, more rapidly afterwards, 

 as we went from the poles toward the circumference of the galaxy. 

 At a distance of 60° from the poles and 30° from the central line or 

 circumference we should see more than twice as many stars per square 

 degree as near the poles. 



The general question of determining the precise position of the 

 galaxy naturally enters into our problem. There is no difficulty in 

 mapping out its general course by unaided eye observations of the 

 heavens or a study of maps of the stars. Looking at the heavens, we 

 shall readily see that it crosses the equator at two opposite points; the 

 one east of the constellation Orion, between 6h. and 7h. of right 

 ascension; the other at the opposite point, in Aquila, between 18h. and 

 19h. It makes a considerable angle with the equator, somewhat more 

 than 60°. Consequently it passes within 30° of either pole. The 

 point nearest of approach to the north pole is in the constellation 

 Cassiopeia. In consequence of this obliquity to the equator, its apparent 

 position on the celestial sphere, as seen in our latitude, goes through 

 a daily change with the diurnal rotation of the earth. In the language 

 of technical astronomy, every day at 12h. of sidereal time, it makes so 

 small an angle with the horizon as to be scarcely visible. If the air is 

 very clear, we might see a portion of it skirting the northern horizon. 

 This position occurs during the evenings of early summer. At Oh. of 

 sidereal time, which during autumn and early winter fall in the evening, 

 it passes nearly through our zenith, from east to west, and can, there- 

 fore, then best be seen. 



Its position can readily be determined by noting the general course 

 of its brighter portions on a map of the stars, and then determining by 

 inspection, or otherwise, the circle which will run most nearly through 

 those portions. It is thus found that the position is nearly always near 

 a great circle of the sphere. From the very nature of the case the 

 position of this circle will be a little indefinite, and probably the esti- 

 mates made of it have been based more on inspection than on compu- 

 tation. The following numerical positions have been assigned to the 

 pole of the galaxy: 



Gould, K. A. = 12h. 41m. Dec.= + 27° 21' 



Herschel, W 12h. 29m. 31° 30' 



Seeliger 12h. 49m. 27° 30' 



Argelander 12h. 40m. 28° 5' 



Were it possible to determine the distance of a star as readily as 

 we do its direction, the problem of the distribution of the stars in space 

 would be at once solved. This not being the case, we must first study 

 the apparent arrangement of the stars with respect to the galaxy, with a 



