20 
is not at all inconsistent with the behaviour of such rings as a 
consequence of their coalescing. 
Saturn with its eight satellites and a ring-system is a specially 
remarkable example, if, according to the Nebular Hypothesis, 
these latter also arose from rings. The ring-system is what is 
left to us of Saturn’s ninth nebulous ring, which has spread and 
become flattened in process of time, and the inner parts of 
which seem destined to fall into the primary, while the outer parts 
will become detached and finally coalesce to form a ninth satel- 
lite. That this satellite should not have been formed from the 
first is explained by the proximity of the ring-system to the 
primary, in consequence of which the opposing centrifugal and 
centripetal forces were so powerfully developed that the ring was 
broken up and an enormous number of diminutive bodies were 
formed instead. 
As for the comets, it is probable that the majority of those 
which have closed orbits were outlying clouds of the original 
nebula, which were never attracted into the main system. 
In conclusion, ocular demonstration alone can transform this 
hypothesis into a law, and the nearest approach to ring-evolution 
is found in Saturn’s system ; but, although it may take years to 
prove or disprove this grand conception, further advances in 
Astronomy seem rather to confirm than refute the leading argu- 
ments of the theory, and for the present, at any rate, these may 
at least be accepted as ‘‘ pegs on which to hang our facts.” 
WEDNESDAY, MAY 13TH. 
THE AURORA BOREALIS AND ALLIED 
PHENOMENA, 
BY 
MR. W. H. REAN, M.R.CSS. 
Among the grand and subiime phenomena of Nature few 
have excited greater wonder and awe among the unlearned, or 
furnished deeper study for the scientific, than the Aurora Borealis. 
Having quoted a graphic description of the Aurora from the 
