few poor springs in the moat would but sustain it as you saw it.
From here I can fill it to the brim.'

'I see,' answered Dorothy. 'But would not a simple overflow serve,
carried from the well through the wall?'

'It would, were there no other advantages with which this mode
harmonised. I must mention one thing more--which I was almost
forgetting, and which I cannot well show you to-night--namely, that
I can use this water not only as a means of defence in the moat, but
as an engine of offence also against any one setting unlawful or
hostile foot upon the stone bridge over it. I can, when I please,
turn that bridge, the same by which you cross to come here, into a
rushing aqueduct, and with a torrent of water sweep from it a whole
company of invaders.'

'But would they not have only to wait until the cistern was empty?'

'As soon and so long as the bridge is clear, the outflow ceases. One
sweep, and my water-broom would stop, and the rubbish lie sprawling
under the arch, or half-way over the court. And more still,' he
added with emphasis: 'I COULD make it boiling!'

'But your lordship would not?' faltered Dorothy.

'That might depend,' he answered with a smile. Then changing his
tone in absolute and impressive seriousness, 'But this is all
nothing but child's play,' he said, 'compared with what is involved
in the matter of this reservoir. The real origin of it was its
needfulness to the perfecting of my fire-engine.'