SCIEKTinC SUMMARY. 
85 
new theory as to the origin of the Leonides. He points out that although 
Uranus could undoubtedly so influence the motion of a single body rising 
from interstellar space as to cause that body to travel in an orbit like 
that of the November meteors, yet, to produce this result, a body must pass 
very close indeed to Uranus to receive the requisite degree of retardation. 
We need not enter into numerical calculations,” he remarks, “ because 
in our ignorance of the actual circumstances under which, according to the 
theory, the members of the meteor system approached Uranus, calculation 
would be more laborious than profitable. But it can readily be shown that to 
produce the retardation required, Uranus must have been within 30,000 miles 
of a body arriving from interstellar space, and eventually travelling in such 
an orbit as that of the November meteors. But this is not all. We know 
that at present the November meteor system, counting only those members 
which travel near enough to the orbit of Tempel’s Comet to come under 
the reasoning here employed, has an extension measured by millions of 
miles in breadth and depth, and by hundreds of millions of miles in length. 
It seems impossible to explain how all these bodies can once have been 
gathered within so small a space that the whole system was set travelling 
on its present orbit by the disturbing influence of Uranus. If ever so com- 
pact, the system should have been able by the mutual attraction of its members 
to maintain its compactness for a very long time— at least not to be scattered 
over a space hundreds of millions of miles long, within the astronomically 
short interval of seventeen centuries. One is thus led to doubt whether the 
November meteors have had an extra-planetary origin at all. They must 
once have been, all in a compact body, so near to Uranus, th t the idea is 
suggested that they came from Uranus ; that in fact he expelled them in 
gome tremendous volcanic outburst. Strange as this may sound, it is after 
all not a whit more strange than the theory (which seems forced upon us 
by other evidence) that meteoric bodies have in some instances been expelled 
from our sun or from his fellow-suns the stars. If we suppose that at any 
former epoch Uranus was in a sunlike state, it would have required no 
greater proportional expenditure of power in that small sun to expel 
meteoric matter than for the central sun to overcome by his explosive 
energy the might of his own gravity. Uranus would have had to impart 
but a velocity of 13-7 miles per second to expel matter from him for ever — 
even if we leave out of account the way in which the sun’s action would 
help in bearing away matter once carried to a certain distance from Uranus. 
It would be a natural consequenoe of such explosive actions as have here 
been suggested, that each of the greater planets would have a dependent 
family of meteor systems, or comets, revolving in orbits approaching very 
near to the orbits of their respective parent planets. We might not, or 
rather we certainly should not, be able to detect from the earth one in many 
hundreds of these dependent comets ; and if any were detected, the 
just inference would be that an enormous number of such comets 
existed. Many comets depending in just such a manner on the planet 
Jupiter have been already detected ; that the case is the same with Neptune; 
that there is one comet at least, which on this view of the matter must be 
regarded as Saturnian ; and that of course the system of bodies I am con- 
sidering would be regarded as a dependent of the planet Uranus. A rather 
