54 ROUGH WAYS MADE SMOOTH. 



specially for intra-Mercurial planets. Thus Professor Hall, 

 of the Washington Observatory, searched over a larger space 

 than is included in fig. 4, without seeing any unknown 

 body. But as he also failed to see many known bodies 

 which should have been seen, it is probable that the search 

 was too harried to be trustworthy. 



It would be satisfactory to be able to say that any of the 

 supposed planets might have been Lescarbault's Vulcan. 

 But in reality, I fear, this cannot have been the case. In 

 the Times, I expressed, in an article dated August 14, 

 1878, the opinion that the evidence obtained establishes 

 the existence of the planet which had so long been regarded 

 as a myth. That opinion was based on a very careful in- 

 vestigation of the evidence available at the time. But it 

 does not accord with what has since been learned respecting 

 Watson's observations. 



We may dismiss planet 3 at once. If Watson is right 

 about this body being distinct from Zeta (a point about 

 which, I must confess, I feel grave doubts), then this must 

 be a planet travelling in an orbit much wider than we can 

 possibly assign to Vulcan. For even at the distance of some 

 seven degrees from the sun it showed no sign of gibbosity. 

 If it had then been at its greatest elongation it would have 

 appeared only half-full. But with the power Watson was 

 using, which enabled him to pronounce that the smaller 

 body near Theta showed no elongation, he would at once 

 have noticed any such peculiarity of shape. He could not 

 have failed to observe any gibbosity approaching to that of 

 the moon when three-quarters full. Moreover on July 29 

 a planet which has its points of crossing the ecliptic 

 opposite the earth's place on April 3 and October 6, 

 could not appear where Watson saw this body (fully two 

 degrees from the ecliptic) unless either its orbit were far 

 wider than that which Leverrier assigned to Vulcan, or else 

 its inclination far greater. Neither suppositicn can be 

 reconciled with Lescarbault's observation. 



With regard to planets j and 2, the case is equally 



