S6 The supposed Intra^Mercurial Planet 



Professor Watson, a well-known and experienced astronomer, 

 who observed the eclipse at Rawlins, Wy., devoted himself 

 to this work, and by help of specially contrived and extem- 

 porised accessories to his equatorial, made a methodical 

 search, which according to accounts already to hand appears 

 to have been, in some degree at least, successful. The first 

 announcement that Professor Watson had discovered Vulcan 

 was received with incredulity, and our veteran English 

 Astronomer Royal thought it highly probable that 6 Gancri 

 had been mistaken for the sought-for planet; you will 

 remember also I stated at a former meeting that although 

 the discovery of an intra-mercurial planet had been notified, 

 it was not by any means received by astronomers as esta-^ 

 blished. More recent advices, however, add considerably to the 

 probabilities that Professor Watson has actually discovered 

 a planet moving inside the orbit of Mercury. The chart 

 shown will give you an idea of the position of the body, as 

 well as that of Gancri when observed, which at once dis- 

 poses of Sir George Airy's suggestion that that star had 

 been mistaken for a planet. Professor Watson says " that 

 while searching with his specially-fitted telescope he came 

 across a ruddy star of the four and a-half magnitude which 

 had a perceptible disc, the magnifying power being only 45." 

 He says also " it was much brighter than 6 Oancri" which is 

 the fifth magnitude. It has been suggested that the object 

 seen might have been a comet, but - Professor Watson spe- 

 cially remarks that "there was no appearance such as 

 would be expected if it had been a comet ;" and further, that 

 he feels warranted in believing it to be an intra-mer- 

 curial planet. Although I do not think this observation 

 alone will establish the existence of a new planet 

 beyond aU doubt, it at all events makes it highly probable, 

 and will stimulate astronomers to avail themselves of every 

 possible chance of ratifying Professor Watson's observation. 

 A Mr. Swift, a well-known American observer of comets, 

 also saw a "strange star," and although the positions he 

 gives do not quite agree with those of Professor Watson, his 

 observation is admitted to be in a great measure cor- 

 roborative. It is pointed out in Nature, No. 463, that 

 a search along the Ecliptic within 10° or 12° each side 

 of the sun with large refractors provided with long 

 dew caps J blackened inside, will aflford the best and 

 probably only chance of recovering Professor Watson's 

 planet, until the total eclipse of 1882. 



