2 Notes on Star- Streams. 



The figure here given to the Milky Way, is that I have 

 adopted in my star-maps, my authorities being chiefly John- 

 stone's Atlas of Modern Astronomy, and SirJ. Herschel's des- 

 cription of the galaxy; but in the northern portion the figure 

 given in the Society's maps has occasionally been followed. I 

 will here epitomize Herschel's description, the most complete 

 yet given. The reader will see that it corresponds closely with 

 the configuration adopted in the illustrative figures. 



The galaxy traverses the constellation Cassiopeia. Thence 

 it throws off a branch towards a Persei, prolonged faintly 

 towards the Pleiades. The main stream, here faint, passes on 

 through Auriga, between the feet of Gemini and the bull's 

 horns, over Orion's club, to the neck of Monoceros. Thence, 

 growing gradually brighter, the stream passes over the head of 

 Canis Major, in a uniform stream, until it enters the brow of 

 Argo, where it subdivides. One stream continues to 7 Argus, 

 the other diffuses itself broadly, forming a fan-like expanse of 

 interlacing branches which terminate abruptly in a line through 

 \ and 7 Argus. Here there is a gap, beyond which the Milky 

 Way commences in a similar fan-shaped grouping, converging 

 on the brilliant (and in other respects remarkable) star, rf 

 Argus. Thence, it enters the Cross by a narrow neck, and then 

 directly expands into a broad, bright mass, extending almost 

 to a Centauri. Within this mass is a singular cavity known as 

 the Coal-sack. At a Centauri the Milky Way again subdivides, 

 a branch running off at an angle of 20°, and losing itself in a 

 narrow streamlet. The main stream increases in breadth, until 

 " making an abrupt elbow/' it subdivides into one continuous 

 but irregular stream, and a complicated system of interlacing 

 streams covering the region around the tail and following claw 

 of Scorpio. A wide interval separates this part of the galaxy 

 from the great branch on the northern side, which is seen in 

 Fig. 2, terminating close on /3 Ophiuchi. 



The main stream, after exhibiting several very remarkable 

 condensations, passes through Aquila, Sagitta, and Vulpecula 

 to Cygnus. In Cygnus there is a "confused and patchy" region, 

 marked by a broad vacancy, not unlike the Coal-sack. From 

 this region there is thrown off the offset to /3 Ophiuchi already 

 mentioned ; the main stream is continued to Cassiopeia. 



There only remains to be noticed " a considerable offset or 

 protuberant appendage," thrown from the head of Cepheus 

 directly towards the pole. 



A word as to the changes in the appearance and position of 

 the Milky Way from month to month, at any given hour. 

 Selecting ten o'clock in the evening, as the most convenient 

 hour, wo have the following variations of configuration : — At 

 the winter solstice the Milky Way passes nearly through the 



