THEIR ARRANGEMENTS AND FORMATION. d 



of the instrument. In one place, where they are more thickly 

 sown than elsewhere, Sir William Herschel reckoned that 

 fifty thousand passed over a field of view two degrees in 

 hreadth in a single hour. It was first surmised by the ancient 

 philosopher, Democritus, that the faintly white zone which 

 spans the sky under the name of the Milky Way, might be 

 only a dense collection of stars too remote to be distinguished. 

 This conjecture has been verified by the instruments of mo- 

 dern astronomers, and some speculations of a most remark- 

 able kind have been formed in connexion with it. By the 

 joint labours of the two Herschels, the sky has been "gauged" 

 in all directions by the telescope, so as to ascertain the condi- 

 tions of different parts with respect to the frequency of stars. 

 The result has been a conviction that, as the planets are parts 

 of solar systems, so are solar systems parts of what may be 

 called Astral Systems that is, systems composed of a multi- 

 tude of stars, bearing a certain relation to eaclT other. The 

 astral system to which we belong 1 , is conceived to be of an ob- 

 long, flattish form, with a space wholly or comparatively 

 vacant in the centre, while the extremity in one direction 

 parts into two. The stars are most thickly sown in the outer 

 parts of this vast ring, and these constitute the Milky Way. 

 Our sun is believed to be placed in the southern portion of the 

 ring, near its inner edge, so that we are presented with many 

 more stars, and see the Milky Way much more clearly, in 

 that direction, than towards the north, in which line our eye 

 has to traverse the vacant central space. Nor is this all. A 

 motion of our solar system with respect to the stars, first 

 suggested by Sir William Herschel, in 1783, has since been 

 verified by the exact calculations of M. Argelander, late 

 director of the Observatory at Abo. The sun is proceeding 

 towards a point in the constellation Hercules. It is, therefore, 

 receding from the inner edge of the ring. Motions of this 

 kind, through such vast regions of space, must be long in 

 producing any change sensible to the inhabitants of our 

 planet, and it is not easy to grasp their general character ; but 

 grounds have nevertheless been found for supposing that not 

 only our sun, but the other suns of the system, pursue a wavy 



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