I S^ 5 -] Comet Systems. igy 
ellipses, or temporarily in parabolas or hyperbolas, round 
other suns.” 
Why, now, should this conclusion be a resultant from the 
fadt that some comets appear to be associated ? Surely it 
does not follow with more certainty that because three comets 
aie tiavelling in company from the region near any one star 
that they emanate from that star, any more than it would 
follow that a single, solitary cornet belonged originally to 
the domain of any star because it happened to be travelling 
away from it. Far be it from me to cast a slur upon the 
useful work which M. Hock has accomplished; but, so far 
as is given me to judge, it is quite certain that he leaves the 
question of the origin of comets, from whence they come 
and whither they go, very much as it was found. And, fur- 
ther than this, the table given above shows that somewhere 
near the year 750 the three comets we are discussing were 
at their nearest to each other ; for if their motions be calcu- 
lated backwards beyond 750 indefinitely, it will be found that 
all three are placed further and further apart the earlier the 
date to which we push our calculations. Thus the comet 
III. ,1860, which was in that year less than half the distance 
of either of the other two from the Sun, would, if our 
inquiry be carried backwards sufficiently beyond 750, be 
found at a distance greatly in excess of the others, in conse- 
quence of its much more rapid rate of motion. The three, 
therefore, could never have started simultaneously upon 
their journey, as M. Guillemin seems to suppose, unless as 
a single comet ; and in this case it is clearly discernible that 
not any more significance attaches itself to their movements 
than to the movements of a comet which retains its entirety. 
Nor is it conceivable that any star could so launch forth 
into space three separate bodies, at different times, that 
their common direction of motion should point towards the 
Sun. Still more impossible of conception is it that their 
separate velocities should be so adroitly imparted that all 
three were caused to join company at one time (some 
thousands of years after the commencement of their journey, 
probably), and in one spot. 
Does it not seem more likely, then, that all three are the 
remains of a shattered comet ? We know that comets have 
broken up almost under the very eyes of astronomers, and 
there is every reason to suppose that a similar catastrophe 
has happened in this case. Ephorus, the Greek historian, 
mentions that the comet of 371 B.C. divided into two ; 
Kepler likewise speaks of the possible duplication of a comet 
which he observed, and got well ridiculed for his pains ! 
