NEW PLANETS NEAR THE SUN. 45 



every year, and there would generally be four transits ; the 

 average number of transits would be about eleven in three 

 years. With a wider orbit and a greater inclination transits 

 would be fewer ; but even with the widest orbit and the 

 greatest inclination that can possibly be allowed, there 

 would be at least one transit a year on the average. 



Now when we remember that, so far as the northern 

 hemisphere is concerned, the sun is observed on every fine 

 day in almost every country in Europe and in half the States 

 of the American Union, to say nothing of observations in 

 Asia, where England and Russia have several observatories, 

 while in the southern hemisphere there are many observa- 

 tories, in Australia, South Africa, and South America (on 

 both side of the Andes), we see how exceedingly small must 

 be the chance that Vulcan could escape detection even for 

 a single year. Far less could Vulcan have escaped all the 

 years which have elapsed since Lescarbault announced his 

 discovery, to say nothing of all the observations made by 

 Carrington, Schwabe, and many others, before the year 1860. 

 If Vulcan really exists, and really has the dimensions and 

 motions described by Lescarbault, the planet must long ere 

 this have been repeatedly seen upon the sun's disc by expe- 

 rienced observers. 



As a matter of fact, Wolf has collected nineteen obser- 

 vations of dark bodies unlike spots on the sun, during the 

 interval between 1761 and 1865. But as Professor New- 

 comb justly points out, with two or three exceptions, the 

 observers are almost unknown as astronomers. In one 

 case at least the object seen was certainly not a planet, since 

 it was described as a cloud-like appearance. ' On the other 

 hand,' says Newcomb, * for fifty years past the sun has been 

 constantly and assiduously observed by such men as Schwabe, 

 Carrington, Secchi, and Sporer, none of whom have ever 

 recorded anything of the sort. That planets in such numbers 

 should pass over the solar disc, and be seen by amateur as- 

 tronomers, and yet escape all these skilled astronomers, is 

 beyond all moral probability.' 



