134 PLEASANT WA YS IN SCIENCE. 



attraction multiplied by eight, or twice our former estimate. 

 We cannot suppose the nebula to be much nearer than 

 the nearest star. Again, we cannot suppose that the light 

 of these gaseous nebulae comes from some bright orb within 

 them of only starlike apparent dimensions, for in that case 

 we should constantly recognize such starlike nucleus, which 

 is not the case. Moreover, the bright-line spectrum from 

 one of these nebulae comes from the whole nebula, as is 

 proved by the fact that if the slit of the spectroscope be 

 opened it becomes possible to see three spectroscopic 

 images of the nebula itself, not merely the three bright lines. 

 So that, if we assume the so-called star in Cygnus to 

 be now like other objects giving the same monochromatic 

 spectrum and this seems the only legitimate assumption 

 we are compelled to believe that the light now reaching us 

 comes from a nebulous mass, not from the faintly luminous 

 envelope of a dead sun. Yet, remembering that when at its 

 brightest this orb gave a spectrum resembling in general 

 characteristics that of other stars or suns, and closely re- 

 sembling even in details that of stars like Gamma Cassio- 

 peise, we are compelled by parity of reasoning to infer that 

 when the so-called new star was so shining, the greater 

 part of its light came from a sunlike mass. Thus, then, 

 we are led to the conclusion that in the case of this body 

 we have a nucleus or central mass, and that around this 

 central mass there is a quantity of gaseous matter, 

 resembling in constitution that which forms the bulk of the 

 other gaseous nebulae. The denser nucleus ordinarily shines 

 with so faint a lustre that the continuous spectrum from its 

 light is too faint to be discerned with the same spectroscopic 

 means by which the bright lines of the gaseous portion are 

 shown; and the gaseous portion ordinarily shines with so 

 faint a lustre that its bright lines would not be discernible 

 on the continuous background of a stellar spectrum. 

 Through some cause unknown possibly (as suggested in 

 an article on the earlier history of this same star in my 

 " Myths and Marvels of Astronomy ") the rush of a rich 



