x86 Comet Systems. [April, 
Dutch astronomer of repute. These results seem to indicate 
that many comets do travel in systems, even as do the tiny 
meteors which circulate in common orbits around the Sun. 
The 'following table exhibits a specimen of one of these 
systems, showing the relative distances, at different times, 
with respeCt to the Sun, of the comets which compose it. 
This, also, I quote from the above-mentioned work. 
Distances from the Sun in Radii of the Earth's Orbit. 
Date. 
Comet i860, III. 
1863, I. 
1863, VI. 
757 '° 
600 
600-4 
6oo"2 
1020*9 
500 
500-6 
500-4 
1259-6 
400 
400-7 
400-5 
I470-0 
300 
300-9 
300*8 
1647-8 
200 
201*1 
201*2 
I 7 ^ 5 ' 1 
100 
ioi*8 
102*1 
18337 
50 
52-8 
53*3 
1853*6 
20 
24*4 
2 5'5 
1858-0 
10 
i 5’9 
I 7‘4 
By this table it will be seen that whilst the three comets 
whose positions are here shown were in 1858 situated 
respectively at a distance of 10, 15-9, and 17-4 radii of the 
Earth’s orbit from the Sun, they were in the year 757 — or 
xxqq years ago — at very nearly equal distances fiom the 
ruling centre of the Solar System. Moreover, their paths 
are directed towards an identical portion of the celestial 
sphere, and, besides, their orbits differ but little from each 
other, being appreciably parabolic. 
Now these faCts are sufficiently surprising : they seem to 
show beyond doubt that these three comets are related and 
of common origin. Furthermore, the same remark will 
apply to several other cases, including not only the transitory 
visitors (as these may be) from interstellar space, but also 
several others which belong to the Sun’s family. 
But it appears to me that the conclusions founded upon 
the labours* of the Dutch astronomer are somewhat far- 
fetched. Thus, we are told, almost it would seem as though 
the faCt depended upon comets moving in systems, that 
“ every star is associated with a cometary system of its own ” 
(the italics are mine) ; “ but owing to the attraction of 
planetary or other matter these bodies continually leave 
their proper primaries, and revolve either permanently in 
