OF ARTS AND SCIENCES : MAY 26, 1863. 145 



amount of deviation from Avliich the angle of position was computed is 

 very small. 



But that the companion of Sirius may produce the disturbances, 

 it, the faint object barely visible in the largest class of telescopes, must 

 have a mass nearly two thirds that of Sirius itself. It is difficult to 

 believe this ; but, as the evidence of this year (1863) shows, Ave may 

 be compelled to do so. 



There are three hypotheses logically possible with respect to the 

 new star. It may be either unconnected with the system of Sirius, or, 

 secondly, a satellite but not the disturbing body, or, thirdly, the dis- 

 turbing body itself. On the first hypothesis, the proper motion of 

 Sirius itself would put it in the following position, assuming the angle 

 of position 84°.5, for 1862.2, and distance ]0".19 for the same date, the 

 latter being the mean of these results (excluding Lassell's 4".92, which 



is quite wrong). ^^ 



10.09 Rutherfurd,* 



10.07 Bond.t 

 10.41 Chacornac.|: 

 Position and Distance by Hypothesis I. ; assuming the little star to 

 be fixed. ^ ,, 



1863.0 79.1 10.80 



1864.0 73.3 11.69 



The second hypothesis gives no ground for calculation, and it will 

 be considered further on. 



The third hypothesis would give (correcting my own investigation, 

 so as to agree in 1862.2 with observation, by -j- 0°.9). 



* American Journal of Science for May, 1863, p. 407. 

 t Astronoinische 2fachrichten, No. 1374. 

 X Ibid., No. 135.5. 



§ MS. furiii.-hed by Professor Bond. 



II As before, American Journal of Science for May, 1863, p. 407. 

 VOL. YI. 15 



