CHAPTERS ON THE STARS. 417 



o'Orionis the motion is established; in those of y and 2, it is more or less 

 probable, but not at all certain; in all the other cases it is too small to be 

 measured. 



This minuteness of the motion makes it probable that these stars are 

 very distant from us, an inference which is confirmed by the smallness 

 of their parallaxes. The careful and long-continued measures of Gill 

 show no parallax to Eigel, while Elkin finds one of only 0".02 to 

 oc Orionis. 



The general conclusion from our examination is this: The ag- 

 glomeration of the lucid stars into clusters does not, in the cases where it 

 is noticeable to the eye, extend to the fainter stars. 



Let us now study the question on the opposite side. The plani- 

 spheres show regions of great paucity in lucid stars; is there here any 

 paucity of telescopic stars? 



The two regions of greatest paucity are near the equator; one ex- 

 tends through the hour of of E. A.; the other from 12h. 20m. to 12h. 

 40m. The richness of these and of the adjoining regions may be in- 

 ferred from Boss's zone of the A. GL Catalogue, including a belt from 1° 

 to 5° of declination. The number of stars in each hour from 23h. to 

 3h. is as follows: 



In 23h. : 271 stars. 



In Oh. : 293 stars. 



In lh. : 299 stars. 



In 2h. : 295 stars. 



These numbers show no paucity in the hour 0, and no excess in the 

 hour 2, which is much richer in lucid stars than the hour 0. 



In the strip from 12h. 20m. to 12h. 40m. the catalogue contains sev- 

 enty-eight stars, a richness of 234 to the hour. In the hour preceding 

 there are 211 stars; in that following, 225. There is, therefore, no pau- 

 city in the strip in question. 



THE STRUCTURE OF THE MILKY WAY. 



The most salient problems suggested by the appearance of the Milky 

 Way are to be approached on lines quite similar to those followed in 

 the last chapter. We begin with a description of this wonderful object 

 as it appears to the observer. We recall that it can be seen through 

 some part of its course on any clear night of the year, and in the eve- 

 ning of any season except that of early summer. We begin with the 

 portion which will be visible in the late summer or early autumn. We 

 can then trace its course southward from Cassiopeia in the northwest. 

 It passes a little east of the zenith down to Sagittarius, near the south 

 horizon. This portion of the belt is remarkable for its diversity of 

 structure and the intensity of the brighter regions. 



In Cassiopeia it shows nothing remarkable, but above this constella- 



VOL. LVIII.— 2 7 



