THE INTRA-MERCURIAL PLANETS. 717 



And now comes another American astronomer, Mr. Swift, who also 

 announces that during the same total eclipse he observed simultaneous- 

 ly in the field of his telescope two stars, of which the one was Theta 

 Cancri, and the other a planet shining with the luster of a star of the 

 fifth magnitude, and whose position he estimates approximately to be, 

 right ascension ^ 26"" 40% declination + 18° 30' 35", a position very 

 near to that of the star seen and determined by Mr. Watson. 



The eclipse of July 29th last, one of the most remarkable of the 

 present century for the duration of totality, was observed all along the 

 zone of centrality (which passed across North America), by a great 

 number of able astronomers, both American and English. Nearly all of 

 these searched for a new star in the neighborhood of the sun, but, with 

 the exception of the two named above, all declare that they saw no- 

 thing beyond the stars rendered momentarily visible by the obscuration 

 of the sun's light. 



Are we thence to conclude that the testimony of these two observers 

 must be rejected ? By no means. But between this and the conclusion 

 that the two stars signalized by Watson are in fact two planets travel- 

 ing between Mercury and the sun, is a long way. Of these two stars, 

 the second, it is supposed, can not be the star Zeta Cancri, whose position 

 is S'^- ff- 12^ and 18° 2'. 



The difference of three minutes is no doubt very great, but when 

 we take account of the haste of observation, and the doubt expressed 

 by the observer himself with regard to its exactness and the possible 

 derangement of his telescope by the action of the wind, this star must 

 not be dismissed without seeing whether or not it will explain the ob- 

 servations. Now, supposing an error of three minutes more or less, the 

 position of the first star becomes S*"- 24°^ and 18° 16', and this is very 

 nearly the position of the star Theta Cancri. 



All that is needed to show how probable is this explanation is to 

 take up a celestial atlas and to locate the sun at the point where it was 

 at the moment of the eclipse, i. e., in front of Delta Cancri (which was 

 visible through the aureolar corona of the eclipsed sun, at its eastern 

 margin). 



We have reproduced in the figure the aspect of the heavens during 

 totality. 



1 is Mercury, 5 is Procyon, 



2 is Regulus, 6 is Pollux, 



3 is Mars, 7 is Castor, 



4 is the sun in eclipse, 8 is Venus. 



In the immediate vicinity of the sun we have inserted at the points 

 «, 5, c, the three stars Delta, Theta, and Zeta Cancri. In our opinion 

 the two stars h and c are the ones which might have been taken for 

 two planets by the American observers. No doubt this hypothesis is a 

 rather bold one, but then the hastiness, the difficulty, and the vagueness 

 of the observation justify it. 



