THE GALAXY. 553 



THE MILKY WAY. 



The Galaxy is familiar to all readers, and although visible all the year 

 round, is perceived more plainly in August, September, and October, or at 

 the beginning and ending of that period. This zone of stars was of course 

 well known to the ancients, but it is to Galileo that we owe the first 

 important information about the Galaxy ; he decided that it was formed of 

 stars. Sir John Herschei investigated the subject very closely, and to him 

 much of the information concerning the Milky Way is due. 



It is not very distinct in the north, but as it advances from Cepheus 

 southwards by the Unicorn, it gets clearer, and opens out in Argo, and 

 descends still south, becoming brighter near the Southern Cross. It then 

 passes northward again, dividing into two branches, one of which dies out, 



Fig. 6 2 8.-The Milky Way. 



and then over Sagittarius, and so on to Cygnus, then to Casseopeia and the 

 starting-point. The number of stars in the Galaxy is about 1 8,000,000. 



In this wonderful zone of stars the centre of our system, the sun, is 

 placed. It was supposed to be divided as in the diagram above ; the inner 

 portion being the stars seen in their thickness, and the outer ring representing 

 the stars viewed in the direction of the length and breadth. But afterwards, 

 Herschei modified his opinions respecting the Milky Way, and since his 

 death many astronomers and Mr. Proctor more particularly have devoted 

 considerable time to an examination of this wonderful zone of stars ; which, 

 it must be remembered, is not a continuous stream; it is a series of luminous 

 patches. On this point Professor Nichol says : 



" It is only to the most careless glance that the Milky Way appears a 



