Comet Systems. 
[April, 
188 
But in our own time a phenomenon precise! 
occurred the circumstances of which aie bnti y , 
-On February a7 th, i8*6, a comet was discovered by Btela 
at Johannisberg, and was afterwards found to _t^vel >n > 
orbit of 6| years’ duration. Since then it has, witn o y 
one exception, been observed at every approach to the Su ."’ 
ud to the yea; 1846, in which year it split up into two dis- 
tinct narts. Both of these receded from each other u 
the middle of February, when they were separated by an 
interval of 190,000 mill After this time they^pproache^ 
scSyVhe distance' betweenfhem'barely exceeded 170,000 
miles o y r thereabouts. In 1852 (their last observed appear- 
ance), however, they were found to have ,j r * ve , e Stance 
considerably during their period of invisibility, the dist 
having increased to 1,500,000 miles And m short t y 
may now, if still existing, be regarded as totally distinct 
Now if phenomena such as this are possible, is it not also 
possible that the three comets mentioned above "^regene- 
rated .similarly ? For what is to prevent Biela s com t o 
anv other from dividing yet again ? In fadt, foi all we kno 
to the contrary, a comet may carry on the process of dupli- 
cation until, for want of bulk, a further division is no on e 
possible. Analogy would lead us to mfei if such is 
rntop that this triple system of Hock staited into existence, 
C a r a system in 0 P r nir the year 750 at a distance of-.n 
„ j „ 1 . rn | 1 prq cy 000 000,000 miles from the bun. nence 
if thfs e”pirat.o 5 n be admitted-and it is obviously more 
1 u„ than the other — it is clear that the meiefadt otth 
existence of a system of comets teaches us nothing respecting 
ZTrthplace o? these “vagabonds’’ 
Another point needs to be noted. The thiee comets le 
ferred to are travelling, as I have said, in orbits appieciabl) 
parabolic Now nothing but a combination of most favourable 
circumstances would enable a comet to describe a stndtty 
parabolic orbit round any star. For let us suppose it to 
travelling alone with any velocity before it arrived undei t 
Influence of any foreign sun. Then this velocity it would 
never lose unfess by accident ; and the velocity imported 
by its ruler for the time being would be additional, and, 
after a time terminable. For no sun can command a velo- 
city greater’ than it can generate: thus, since the come 
would always retain its own native velocity in addition to 
that enforced by any extraneous power, the two velocities 
combined would supply the speed necessary to carry it back 
