of the Sun and Solar Syjlem . 275 
may be attributed to the imperfe&ion of the inftrument ; but 
that when it amounts to 10 or 15", it is a very probable indica- 
tion of a proper motion. of fuch a (far. He adds, that when 
the difagreement is fo much as in fome ftars which he names, 
(among which is fomahand, where the difference is 21" in co 
years) he has not the leaft doubt of a proper motion 
By this extenfive table I thought it highly neceffary imme- 
diately to examine the hypothecs of the motion of the folar 
fyftem, that it might receive an early check from obfervations, 
if they fhould be unfavourable ; or that, on the other hand, it 
might be fupported by the additional evidence of more ftars, 
if their apparent proper motions fhould coincide with the idea I 
have pointed out in my paper on this fubje£t. 
I have followed Mr. mayer’s judgement of his own and 
roemer’s obfervations,- and left out of the lift all the ftars that 
do not fhew a difagreement amounting to io // in the places 
which are given for them in 1706 and 1756. I have alfo left 
out thofe 13, or rather 14 ftars, which have already been exa- 
mined in my paper, and have been fhewn to fupport the hypo- 
thecs 1 have advanced : the reft are here drawn up in two tables. 
The firft contains the ftars that agree with my affigned motion 
of the folar fyftem ; or rather which are thereby refolved into 
apparent, or partly, apparent, and partly proper motions. The 
fecond table contains thofe ftars whole motions cannot be ac- 
counted for by my hypothecs, and muft therefore be aferibed 
to a real motion in the ftars themfelves, or to fome fill more 
hidden caufe of a ft ill remoter parallax -f • 
* De motu fixarum proprio Ccmmentatio. Op. inecl. Vol. I. p. 79. 
f That 1 may not be obfeure, it will be proper to mention what I allude to, 
especially as it claims a diftant connection with our fubjeft, and may hereafter 
become of Sufficient moment to engage our attention. Mr. michell’s admirable 
idea 
