Again she looked at the moat, and then her eyes wandered away over
the castle. The two courts and their many roofs, even those of all
the towers, except only the lofty watch-tower on the western side,
lay bare beneath her, in bright moonlight, flecked and blotted with
shadows, all wondrous in shape and black as Erebus.

Suddenly, she knew not whence, arose a frightful roaring, a hollow
bellowing, a pent-up rumbling. Seized by a vague terror, she clung
to the parapet and trembled. But even the great wall beneath her,
solid as the earth itself, seemed to tremble under her feet, as with
some inward commotion or dismay. The next moment the water in the
moat appeared to rush swiftly upwards, in wild uproar, fiercely
confused, and covered with foam and spray. To her bewildered eyes,
it seemed to heap itself up, wave upon furious wave, to reach the
spot where she stood, greedy to engulf her. For an instant she
fancied the storming billows pouring over the edge of the
battlement, and started back in such momentary agony as we suffer in
dreams. Then, by a sudden rectification of her vision, she perceived
that what she saw was in reality a multitude of fountain jets
rushing high towards their parent-cistern, but far-failing ere they
reached it. The roar of their onset was mingled with the despairing
tumult of their defeat, and both with the deep tumble and wallowing
splash of the water from the fire-engine, which grew louder and
louder as the surface of the water in the reservoir sank. The uproar
ceased as suddenly as it had commenced, but the moat mirrored a
thousand moons in the agitated waters which had overwhelmed its
mantle of weeds.

'You see now,' said lord Herbert, rejoining her while still she
gazed, 'how necessary the cistern is to the keep? Without it, the