bsorb the whole of the sun's share by quite an
insignificant enlargement of its present path. It does not seem likely
that the distribution that must ultimately take place can much affect
the present configuration of the system.

We thus see that the tides do not appear to have exercised anything
like the same influence in the affairs of our solar system generally
which they have done in that very small part of the solar system which
consists of the earth and moon. This is, as I have endeavoured to show
in these lectures, the scene of supremely interesting tidal phenomena;
but how small it is in comparison with the whole magnitude of our
system may be inferred from the following illustration. I represent
the whole moment of momentum of our system by L1,000,000,000, the bulk
of which is composed of the revolutional moments of momentum of the
great planets, and the rotational moment of momentum of the sun. On
this scale the rotational share which has fallen to our earth and moon
does not even rise to the dignity of a single pound, it can only be
represented by the very modest figure of 19_s._ 5_d._ This is divided
into two parts--the earth by its rotation accounts for 3_s._ 4_d._,
leaving 16_s._ 1_d._ as the equivalent of the revolution of the moon.
The other inferior planets have still less to show than the earth.
Venus can barely have more than 2_s._ 6_d._; even Mars' two satellites
cannot bring his figure up beyond the slender value of 1-1/2_d._;
while Mercury will be amply represented by the smallest coin known at
her Majesty's mint.

The same illustration will bring out the contrast between the Jovian
system and our earth system. The rotational share of the former would
be totally represented by a sum of nearly L12,000; of this, however,
Jupiter's satellites only contribute about L89, notwithstanding that
there are four of them. Thus Jupiter's satellites have not one
hundredth part of the moment of momentum which the rotation of Jupiter
exhibits. How wide is the contrast between this state of things and
the earth-moon system, for the earth does not contain in its rotation
one-fifth of the moment of momentum that the moon has in its
revolution; in fact, the moon has gradually robbed the earth, which
originally possessed 19_s._ 5_d._, of which the moon has carried off
all but 3_s._ 4_d._

And this process is still going on, so that ultimately the earth will
be left very poor, though not absolutely penniless, at leas