148 cosmos. 



tic nearly in the solstitial colure), and thence over Orion's 

 club to the neck of Monoceros, intersecting the equinoctial 

 (in 1800) at R. A. 6h. 54m. From this point the brightness 

 considerably increases. At the stern of Argo one branch 

 runs southward to y Argus, where it terminates abruptly. 

 The main stream is continued to 33 S. Decl., where, after 

 separating in a fan-like shape (20 in breadth), it again 

 breaks off, so that there is a wide gap in the Milky Way in 

 the line from y to A Argus. It begins again in a similar 

 fan-like expansion, but contracts at the hind feet of the Cen- 

 taur and before its entrance into the Southern Cross, where 

 it is at its narrowest part, and is only 3 or 4 in width. 

 Soon after this the Milky Way again expands into a bright 

 and broad mass, which incloses f3 Centauri as well as a and 

 (3 Crucis, and in the midst of which lies the black pear- 

 shaped coal-sack, to which I shall more specially refer in the 

 seventh section. In this remarkable region, somewhat below 

 the coal-sack, the Milky Way approaches nearest to the South 

 Pole. 



The above-mentioned bifurcation, which begins at a Cen- 

 tauri, extended, according to older views, to the constellation 

 Cygnus. Passing from a Centauri, a narrow branch runs 

 northward in the direction of the constellation Lupus, w r here 

 it seems gradually lost ; a division next shows itself at y 

 Normse. The northern branch forms irregular outlines till 

 it reaches the region of the foot of Ophiuchus, where it wholly 

 disappears ; the most southern branch then becomes the 

 main stream, and passes through the Altar and the tail of 

 the Scorpion, in the direction of the bow of Sagittarius, 

 where it intersects the ecliptic in 276 long. It next runs 

 in an irregular patchy and winding stream through Aquila, 

 Sagitta, and Vulpecula up to Cygnus ; between e, a, and y, 

 of which constellation a broad dark vacuity appears, which, 

 as Sir John Herschel says, is not unlike the southern coal- 

 sack, and serves as a kind of center for the divergence of 

 three great streams.* One of these, which is very vivid and 

 conspicuous, may be traced running backward, as it were, 

 through (3 Cygni and c Aquilae, without, however, blending 

 with the stream already noticed, which extends to the foot 

 of Ophiuchus. A considerable offset or protuberant append- 

 age is also thrown off by the northern 'stream from the head 



* Outlines, p. 531. The strikingly dark spot between a and y Cas- 

 siopeia i9 also ascribed to the contrast with the brightness by' which it 

 is surrounded. See Struve, Etudes St ell., note 58. 



