of the Companion of Sirius. 



67 



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 

 S3'stem of Sirius; or, secondly, a satellite, but not the dis- 

 turbing body ; or, thirdly, the disturbing body itself. On 

 the first hypothesis, the proper motion of Sirius itself would 

 put it in the following position, assuming the angle of posi- 

 tion 84°'5, for 1862-2, and distance lC-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,J 



Position and Distance by Hypothesis I. ; assuming the 

 little star to be fixed. 



1863 0 79 1 10-80 



18640 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 in- 

 vestigation, so as to agree in 1862*2 with observation, by 

 + 0°-9). 



18630 83°5 

 1864-0 821 



Observation gives, compared with these hypotheses, 



1863-3 Bond,§ 82 8 Hyp. I. 77-4 Hyp. III. 831 



1863-2 Rutherfurd,!! 812 77*9 83-2 



Computed — Observed. 

 I. III. 



Bond, -5-4 + 0-3 



Eutherfurd, - 3-3 + 20 



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

 t Astronomische Nachrichten, No. 1374. 

 X Ibid. No. 1355. 



§ MS. furnished by Professor Bond. 



Ij As before, American Journal of Science for May 1868, p, 407. 



