MILKY WAY. 



followed by means of a map of the stars, or a celestial globe, 

 upon which it is delineated, that it will be needless here to 

 describe it. 



74. When this nebulous whiteness is submitted to telescopic 

 examination with instruments of adequate power, it proves to be a 

 mass of countless numbers of stars, so small as to be individually 

 undistinguishable, and so crowded together as to give to the place 

 they occupy the whitish appearance from which the milky way 

 takes its name. 



Some idea may be formed of the enormous number of stars 

 which are crowded together in those parts of the heavens, by 

 the actual numbers so distinctly visible as to admit of being 

 counted or estimated, which are stated by Sir W. Herschel to 

 have been seen in spaces of given extent. He states, for example, 

 that in those parts of the milky way in which the stars were most 

 thinly scattered, he sometimes saw eighty stars in each field. In 

 an hour, fifteen degrees of the firmament were carried before his 

 telescope, showing successively sixty distinct fields. Allowing 

 eighty stars for each of these fields, there were thus exhibited, in 

 a single hour, without moving the telescope, four thousand eight 

 hundred distinct stars ! But by moving the instrument at the 

 same time in the vertical direction, he found that in a space of 

 the firmament, not more than fifteen degrees long, by four broad, 

 he saw fifty thousand stars, large enough to be individually 

 visible and distinctly counted ! The surprising character of this 

 result will be more adequately appreciated, if it is remembered 

 that this number of stars thus seen in the space of the heavens, 

 not more than thirty diameters of the moon's disc in length, and 

 eight in breadth, is fifty times greater than all the stars taken 

 together, which the naked eye can perceive at any one time in the 

 heavens, on the most serene and unclouded night ! 



On presenting the telescope to the richer portion of the via 

 lactea, Herschel found, as might be expected, much greater num- 

 bers of stars. In a single field he was able to count 588 stars ; and 

 for fifteen minutes, the firmament being moved before his tele- 

 scope by the diurnal motion, no diminution of number was 

 apparent ; the number seen at any one time being greater than 

 can be seen by the naked eye, on the entire firmament, except on 

 the clearest nights. 



75. It may be considered as established by a body of analogical 

 evidence, having all the force of demonstration, that the fixed 

 stars are self-luminous bodies, similar to our sun ; and that 

 although they may differ more or less from our sun and from each 

 other in magnitude and intrinsic lustre, they have a certain ave- 

 rage magnitude ; and that, therefore, in the main, the great 



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