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stars are really fixed, as their popular name supposes ; or 
whether they, like all the minor bodies, have their own special 
orbits and revolutions. He says : — 
“The fact that some of these stars had a distinct and separate 
motion, indicating a permanent change of their position relatively 
to the sun, was first discovered by Edmund Halley. Some 
observations of the three brilliant stars, Sirius, Arcturus, and 
Aldebaran, made by the old Egyptian astronomers, had fortu- 
nately been handed down to his time ; and, on looking over 
them, he perceived that those stars must have shifted their 
positions since that early time, by a small but well-marked 
amount. This indicated that either these stars, or the sun, or 
probably both, must have changed their places by many millions 
of miles since those old records had been penned by the philo- 
sophers of Alexandria. Other astronomers followed in Halley’s 
track ; and, by the beginning of this century, the proper motion 
of more than a hundred stars had been determined, chiefly by 
comparing them with Tycho Brahe’s catalogue, made out two 
hundred years before. These proper motions showed great 
differences in amount and direction; and no attempt was made 
to reconcile and systematize them until the subject was taken 
up by the bold and speculative genius of Sir William Herschel, 
who revelled in difficulties, and whose daring and ambitious 
spirit always selected the loftiest and apparently most hopeless 
themes. He succeeded in evoking order out of apparent con- 
fusion and chaos; and announced his discovery of the fact that 
the sun, with all his gorgeous following, is sweeping majestically 
through space in the direction of the constellation Hercules. 
It was not till fifty years afterwards that another astronomer 
was found bold enough to grapple with this mighty theme. It 
was then taken up by some of the leading astronomers of Russia, 
with the advantage of half a century’s additional observations, 
and Herschel’s results were confirmed in the fullest manner 
possible. 
“ Of course the other suns of our great cluster have their own 
motions also; their varying position relatively to ourselves 
depending partly upon our motion, and partly on their own. 
Mathematical theory, proceeding upon Newton’s great law, tells 
us that the centre of this universal motion must be the centre of 
gravity of the whole stellar cluster; that any star situated there 
must be at rest, while all the others are circling in ceaseless 
revolution around it. Madler, of Dorpat, is the only astronomer 
who has ventured to seek for this central sun. By studying 
Herschel’s diagram of the stellar system, and combining it with 
the known direction of our sun’s motion, this philosopher was 
led to believe that the centre of gravity of that system must be 
