xiv President's Address 



and when I tell you it has continued its usual work in 

 astronomy, meteorology, terrestrial magnetism, and other 

 matters kindred to these, you will be assured that neither 

 observers nor instruments have had time to rust. 



I have on previous occasions referred to the supposed 

 existence of a planet or planets between Mercury and the 

 sun ; and last session I gave a brief account of the reported 

 actual discovery during the eclipse of July 29th, 1878, of 

 such a body by Professor Watson, a well-known and skilled 

 American astronomer. At the time, and indeed since, con- 

 siderable doubt has been expressed by astronomers generally 

 as to whether the body seen during the darkness of totality 

 was really a planet, or, indeed, anything but one of the 

 known stars of the constellation Cancer ; and in one of the 

 " Notes from the Observatory" I alluded to the disbelief in 

 this discovery expressed by another well-known American 

 astronomer. Professor Watson replies to the criticisms on 

 his observations in the columns of the Astronomische Nach- 

 richten, and states most emphatically that the two stars he 

 observed during totality were new, and not any of the 

 known stars of Cancer ; and he, moreover, shows that the 

 conclusions arrived at by his critics as to his mode of obser- 

 vation are altogether erroneous, He says : — " Whether or 

 not the two new objects which I observed were intra- 

 Mercurial planets, I cannot positively assert, but I certainly 

 have the right to express my honest belief that they are." 

 This letter will probably remove many doubts, and for my 

 part I cannot conceive how so old and skilled an observer as 

 Professor Watson could have made the blunders attributed 

 to him by his critics. The probability of the existence of 

 intra-Mercurial planets is certainly strengthened by these 

 observations. 



Assuming that one of the bodies seen by Professor Watson 

 was really a planet, Dr. Oppolzer, of Vienna, considered it 

 probable that it might cross the sun's disc in February last, 

 and he consequently sent a telegram to southern astrono- 

 mers, requesting a watch to be kept on the sun's disc on a 



