



THE BODIES OF srACE. 



the experiment has been tried, no sensible parallax could 

 be detected ; from which the same inference was to be 

 made in their case. But a sensible parrallax of about 

 one second has been ascertained in the case of the double 

 star, d a, of the constellation of the Centaur,* and one of 

 the third of that amount for the double star, 61 Cygni ; 

 which gave reason to presume that the distance of the 

 former might be about twenty thousand millions of miles, 

 and the latter of much greater amount. If we suppose 

 that similar intervals exist between all the stars we shall 

 readily see that the space occupied by even the compara- 

 tively small number visible to the naked eye must be vast 

 beyond all powers of conception. 



The number visible to the eye is about three thousand ; 

 but when a telescope of small power is directed to the 

 heavens, a great number more come into view, and the 

 number is ever increased in proportion to the increased 

 power of the instrument. In one place, where they are 

 more thickly sewn than elsewhere,- Sir William Herschel 

 reckoned that fifty thousand passed over a field of view 

 two degrees in breadth in a single hour. It was first sur- 

 mised 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 modern astrono- 

 mers, and some speculations of a most remarkable kind 

 have been formed in connexion with it. By the joint 

 labors of the two Herschels, the sky has been " gauged" 

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

 conditions of different parts with respect to the frequency 

 of the stars. The result has been a conviction that, as 

 the planets are parts of the solar systems, so are solar sys- 

 tems parts of what may be called astral systems — that is, 

 systems composed of a multitude of stars, bearing a cer- 

 tain relation to each other. The astral system to which 

 we belong, is conceived to be of an oblong, flattish form, 

 with a space wholly or comparatively vacant, in the cen- 

 tre while the extremity to 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 



* By Mr. Henderson, Professor of Astronomy in *he Edinburgh 

 V aiversity, and Lieutenant Meadows. 



