CONSOLIDATION OF NEBULA 231 



would "remain expanded about the nucleus in the 

 shape of a very extended atmosphere ; or it may be of 

 an elastic nature, and be kept from uniting with the 

 nucleus, as their elasticity causes the atmospheres of 

 the planets to be expanded about them. In this case 

 we have another property of the nebulous substance to 

 add to the former qualities of its matter." 



No one can read even an outline of these interesting 

 speculations by an adventurer into the workshops of 

 creation, without feeling awed by the boldness and 

 sublimity of his views, as well as desirous of knowing 

 what else he saw in his magic mirror, or thought he 

 saw, of the machinery in motion. What he has told 

 us of a mighty volume of nebulous matter is that " a 

 nucleus, to which these nebulae seem to approach, is an 

 indication of consolidation," and that the faintness 

 of the light in the parts outside the nucleus arises from 

 " a gradual diminution of the length and density of the 

 nebulous matter, occasioned by its gravitation towards 

 the nucleus into which it probably subsides." 1 He 

 believes that " a pretty bright round nebula about a 

 quarter or one minute in diameter, and looking no 

 bigger than a pea, may have shrunk into itself till it is 

 now nineteen hundred times more dense than at first, 

 a proportion of density more than double that of 

 water to air." 1 In another case he calculates that 

 "the condensation may have reduced the nebulous 

 matter to less than the one hundred and twenty-two 

 thousandth part of its former bulk." x To understand 

 what these figures mean, suppose a sphere whose 

 radius is nearly three thousand millions of miles, or as 

 far as from the sun to our outermost known planet, 

 1 Phil. Trans., 1811, pp. 308, 310, 311, 315, 316, 318. 



