MOTION OF THE SOLAR SYSTEM. 
83 
the proper motions of the other stars in Mayer’s table, and shows that, out of forty- 
four stars, the observed motions of thirty-two agree with the hypothesis, while those 
of the remaining twelve cannot be accounted for by it, and “ must therefore he 
ascribed to a real motion of the stars themselves, or to some still more hidden cause 
of a still remoter parallax.” 
It will be remarked that the above result was arrived at without the aid of any 
calculation whatever, nor does it appear that the precise direction of the apparent 
motion of any of the stars was ascertained or taken account of. The author con- 
sidered merely the changes in right ascension and declination, and gave such a di- 
rection to the solar motion as would produce corresponding changes in those two 
directions in the greatest number of instances, without reference to their relative 
amounts, or attempting to produce an exact coincidence of the hypothetical and ap- 
parent directions in any particular case. Nor did he pretend to assign the point 
towards which the sun’s motion is directed w T ith any precision ; “ it is somewhere near 
X Herculis, but may be somewhat more to the north.” 
In the same year (1783) in which Sir W. Herschel’s paper appeared in the Trans- 
actions, Prevost communicated the results of a similar inquiry to the Berlin Aca- 
demy in a memoir which was published in the Nouveaux Memoires of that Society 
for 1781. Prevost’s investigation was also grounded on the proper motions given in 
Mayer’s table. After stating the opinion of Mayer that the observed motions could 
not be explained on the hypothesis of the motion of the solar system, he remarks, 
that on examining the table under every point of view, he had come to an opposite 
conclusion, and found that it did in fact afford indications of such amotion, although 
the true motions of the stars, or, perhaps, some other cause, occasioned exceptions. 
He then selects, from Mayer’s list, twenty-six stars whose variations of position ex- 
ceeded 14" in right ascension or declination, and from a comparison of the whole 
concludes that the apparent motions indicated by the table would be most nearly re- 
presented by supposing the sun’s motion to be directed towards that point of the 
heavens of which the right ascension is 230°, and the declination 25° north, — a con- 
clusion which agrees with that of Sir W. Herschel in respect of declination, but 
differs from it about 2 7° in right ascension. The agreement of the individual obser- 
vations with this result he considered was sufficient to render it probable, first, that 
the solar system is actually moving towards the point indicated, and, secondly, that 
at the present time the stars which are the nearest to the sun are Sirius, Procyon and 
Arcturus ; and he thought the observations also afforded grounds for conjecturing 
that the sun may be describing, in antecedentia, an orbit about Arcturus, or at least 
about a centre of gravity common to those brilliant stars which occupy the quarter 
of the heavens in which the right ascensions appear to diminish, such as Arcturus, 
Regulus, Procyon, Sirius*. 
* Among the inferences drawn by Prevost from the hypothesis of the sun’s proper motion, the following 
may be remarked : — supposing comets to be formed of matter existing beyond our system, but projected so as 
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