A, Hall—Companion of Sirius. 457 
Art. LX.—Noie on the Companion of Sirius ; 
by AsapH HALL. 
In 1844, Bessel showed by a careful discussion of the obser- 
vations of Sirius, that the right ascensions of this star could 
not be represented within the limits of their probable errors 
by means of a uniform proper motion. The residuals were 
distributed in a periodical form; and Bessel, after a simple and 
Ingenious transformation of the equations of motion, and the 
assumption of a value for the annual parallax of Sirius, was led 
to infer the existence of a dark body near this star that dis- 
