Notes on Star -Streams. 11 



milky light comes from orbs really smaller than the seventh 

 magnitude stars in the same field, and clustering round these 

 stars in reality as well as in appearance. 



The observations applied to this spot may be extended to 

 all clusters of globular form; and where a cluster is not globu- 

 lar in form, but exhibits, on examination, either (1) any ten- 

 dency within its bounds to stream-formation, or (2) a uniform 

 increase in density as we proceed from any part of the circum- 

 ference towards the centre, it appears wholly inconceivable 

 that the apparent cluster is — not really a cluster, but — a long 

 range of stars extending to an enormous distance directly from 

 the eye of the observer. When, in such a case, many stars of 

 the higher magnitudes appear within the cluster, we seem 

 compelled to admit the probability that they belong to it ; and, 

 in any case, we cannot assign to the farthest parts of the 

 cluster a distance greatly exceeding (proportionally) that of 

 the nearest parts. 



Of a like character is the evidence afforded by narrow 

 streams and necks within the galactic circle. If we consider 

 the convolutions over Scorpio, it will seem highly improbable 

 that in each of these we see, not a real convolution or stream, 

 but the edge of a roll of stars. For instance, if a spiral roll 

 of paper be viewed from any point taken at random, the 

 chances are thousands to one against its appearing as a spiral 

 curve, and, of course, the chance against several such rolls so 

 appearing is indefinitely greater. The fact that we are assumed 

 to be not very far from the supposed mean plane of the Milky 

 Way would partly remove the difficulty here considered, if it 

 were not that the thickness and extent of the stratum, as 

 compared with the distances of the lucid stars must necessarily 

 be supposed so very great, on the assumption of any approach 

 to uniformity of distribution. 



Evidence pointing the same way is afforded by circular 

 apertures in the galaxy, or indeed by apertures of other forms, 

 since a moment's inspection of Pigs. 3 and 5 will show the 

 improbability of any tunnelling (so to speak) through the star 

 stratum, being so situate as to be discernible from S. Another 

 peculiarity of these cavities is also noticeable ; whereas on the 

 borders of every one there are many lucid stars, or in some 

 cases two or three very bright stars, ivithin the cavity there is 

 a marked paucity of stars. This phenomenon seems to indi- 

 cate a much closer connection between the brighter stars, and 

 the milky light beyond, than is supposed in the stratum theory. 

 One can hardly conceive the phenomenon to be wholly acci- 

 dental. 



There are some other points on which I would fain dwell, 

 but space will not permit me. I may, perhaps, on another 



