de, and
the great inchoate mass separates into two--one about eighty times as
big as the other. The bigger one we now call earth, the smaller we now
call moon. Round and round the two bodies went, pulling each other into
tremendously elongated or prolate shapes, and so they might have gone on
for a long time. But they are unstable, and cannot go on thus: they must
either separate or collapse. Some disturbing cause acts again, and the
smaller mass begins to revolve less rapidly. Tides at once
begin--gigantic tides of molten lava hundreds of miles high; tides not
in free ocean, for there was none then, but in the pasty mass of the
entire earth. Immediately the series of changes I have described begins,
the speed of rotation gets slackened, the moon's mass gets pushed
further and further away, and its time of revolution grows rapidly
longer. The changes went on rapidly at first, because the tides were so
gigantic; but gradually, and by slow degrees, the bodies get more
distant, and the rate of change more moderate. Until, after the lapse of
ages, we find the day twenty-four hours long, the moon 240,000 miles
distant, revolving in 27-1/3 days, and the tides only existing in the
water of the ocean, and only a few feet high. This is the era we call
"to-day."

The process does not stop here: still the stately march of events goes
on; and the eye of Science strives to penetrate into the events of the
future with the same clearness as it has been able to descry the events
of the past. And what does it see? It will take too long to go into full
detail: but I will shortly summarize the results. It sees this
first--the day and the month both again equal, but both now about 1,400
hours long. Neither of these bodies rotating with respect to each
other--the two as if joined by a bar--and total cessation of
tide-generating action between them.

The date of this period is one hundred and fifty millions of years
hence, but unless some unforeseen catastrophe intervenes, it must
assuredly come. Yet neither will even this be the final stage; for the
system is disturbed by the tide-generating force of the sun. It is a
small effect, but it is cumulative; and gradually, by much slower
degrees than anything we have yet contemplated, we are presented with a
picture of the month getting gradually shorter than the day, the moon
gradually approaching instead of receding, and so, incalculable myriads
of ages hence, precipitating itself upon the su