24 * 
Dr. Hercshel on the Direction of the 
Changes in the Position of double Stars . 
We have lately seen that the alterations in the relative 
situation of a great number of double stars may be accounted 
for by a parallactic motion. Among the 56 stars which I have 
given, the changes of more than half of them appear to be of 
this nature ; and it will certainly be more eligible to ascribe 
them to the effect of parallax than to admit so many separate 
motions in the different stars ; especially when it is considered 
that if the alterations of the angle of position were owing to a 
motion of the largest star of each set, the direction of such 
motions must, in contradiction to all probability, tend nearly to 
one particular part of the heavens. 
This argument, drawn from the change of the position of 
double stars, may be considered as deriving its validity from 
the same source with the former, namely, the parallactic 
motions of at least 28 more stars, pointing out the same apex 
of a solar motion by their direction to its opposite parallactic 
center. 
Incongruity of proper Motions. 
It may be remarked that the proper motions of the stars, if 
they were in reality such as they appear to be, would contain 
a certain incongruous mixture of great velocity and extreme 
slowness. Arcturus alone describes annually an arch of more 
than two seconds : Aldebaran hardly one-tenth and a quarter 
of a second : Rigel little more than one-tenth and a half : even 
Lyra moves barely three and a quarter tenths of a second, 
while Procyon has almost four times that velocity. Out of 36 
stars whose proper motion we have examined, there are 15 
that do not reach two-tenths of a second : /3 Virginia moves 
