1874.] The Saturnan System. 9 
the mightiest aggregation of all, on account of the greater 
quantity of matter. Here, then, Jupiter had his birth, chief 
giant of the solar system, and prince of all the planets. 
But the range of sway would widen with increasing distance, 
and at first such widening would go far to counterbalance the 
gradual falling off in the gravity of matter. Moreover, 
with increase of distance from the sun would come a greater 
freedom to form out of the aggregating matter subordinate 
schemes or systems. Next, then, beyond Jupiter, with his 
giant bulk and uniform system of secondary bodies, came 
Saturn into being, inferior in mass to his giant brother, but 
ruling over a wider space, separated from Jupiter by a far 
greater distance than separates Jupiter from the asteroids, 
and in fact, according to the criterion I have laid down above, 
nearly the equal of Jupiter in the range of his independent 
power. Here we see the origin of the most remarkable 
system within the solar domain—a scheme of rings whose 
complicated structure is as yet not half understood, anda 
family of eight satellites as diverse in size and arrangement 
as the eight primary members of the solar family itself; 
and we can readily understand how, with yet increasing 
distances and continually decreasing quantity of matter, the 
minor but still gigantic masses of Uranus and Neptune 
should appear on the outskirts of the solar system. I 
venture to predict, with some degree of confidence, that 
if. any trans-Neptunian planet be ever discovered, it will 
be inferior, but not greatly inferior, to both Uranus and 
Neptune in mass.* 
Let us now, however, turn from the consideration of the 
mass and weight of Saturn, and of the processes by which 
he may be thought to have reached his present condition, 
to the inquiry what that condition probably is. 
We see Saturn, then, the centre of a scheme of wonderful 
extent and importance. The outermost satellite circuits in 
an orbit having a diameter of more than 4,600,000 miles. 
This is the widest span of any satellite orbit, and not far 
short of ten times the span of our moon’s orbit. The widest 
span of the Jovian satellite system amounts to but 2,380,000 
miles, or almost exactly five times the span of the moon’s 
orbit. It will be observed that both the Saturnian and 
* In old times this would have been a tolerably safe prediction, since any 
such planet would have been very unlikely indeed to be discovered. But in 
these days, when the zodiac is continually being swept for the discovery of 
new planets, and when new planets are being detected at an average rate of 
about five per annum, it is exceedingly unlikely that any trans-Neptunian planet 
will long escape detection, supposing any such planet exist to be detected. 
VOL. IV. (N.S.) Cc 
