Then back she sways; and after tottering
Forward, recovers then her seats of poise.
Thus, this is why whole houses rock, the roofs
More than the middle stories, middle more
Than lowest, and the lowest least of all.
Arises, too, this same great earth-quaking,
When wind and some prodigious force of air,
Collected from without or down within
The old telluric deeps, have hurled themselves
Amain into those caverns sub-terrene,
And there at first tumultuously chafe
Among the vasty grottos, borne about
In mad rotations, till their lashed force
Aroused out-bursts abroad, and then and there,
Riving the deep earth, makes a mighty chasm--
What once in Syrian Sidon did befall,
And once in Peloponnesian Aegium,
Twain cities which such out-break of wild air
And earth's convulsion, following hard upon,
O'erthrew of old. And many a walled town,
Besides, hath fall'n by such omnipotent
Convulsions on the land, and in the sea
Engulfed hath sunken many a city down
With all its populace. But if, indeed,
They burst not forth, yet is the very rush