3 88 THE WORLD MACHINE 



therefore imagined one ; and since it would needs be very 

 large and on this account conspicuous, if it were aglow like the 

 rest, he conceived that these vast central suns were opaque 

 and dark. 



It was a pure conceit. There was siniply nothing save a 

 shadowy analogy upon which the imagination of Lambert had 

 to build. His ideas were generally forgotten, or remembered 

 only to be flouted. Simon Newcomb, in his Popular Astronomy, 

 has this rather tart word : 



"As not the slightest evidence favouring the existence of 

 these opaque centres has ever been found, we are bound to 

 say that this sublime idea of Lambert's has no scientific founda- 

 tion. Astronomers have handed it over without reservation 

 to lecturers and essayists/' 



In a way this rebuke is still justified. Still, it is curious 

 to note how, within a very few years, discoveries have come 

 which lend a hint that such opaque centres may exist. These 

 might be the dark suns which the spectroscope has revealed.. 

 Their number, we know already, is great. Whether they be 

 companions of glowing suns or not, there seems little reason 

 to doubt that eventually the number of dark bodies will be 

 found vastly to outnumber those which are ablaze. A sun of the 

 probable grandeur of Canopus would have a mass more than 

 sufficient to form such a centre of the third order ; and on 

 the reasoning indicated, it is much more likely to be dark than 

 luminous. 



Perhaps in another half-century or so, we may have some 

 basis upon which to estimate the validity of Lambert's con- 

 ceptions. At the present time speculative minds may still let 

 their fancy rove. The most vital objection which may be 

 urged against this view, at least so far as our own solar system 

 is concerned, is the apparent absence of any considerable per- 

 turbation of the planets. The motion of the moon, we know, 

 is very sensibly affected by the sun. If we are revolving about 

 some greater sun, it might readily be supposed that it would 

 exercise some gravitational pull upon the larger planets in a 

 similar way. No equivalent deviation from their orbits can 

 be found. It seems fairly certain that there is no body in any 

 wise comparable with the mass of the sun within at least a 

 thousand times the earth's distance. Between this and 277,000 

 times the estimated distance of the nearest sun is, of course, 



