It's just on eleven.

Come on!' And Oswald said, 'Where to ?' This was the beginning of it.
The moat that is all round our house is fed by streams.

One of them is a sort of open overflow pipe from a good-sized stream that flows at the other side of the orchard.
It was this stream that Alice meant when she said-- 'Why not go and discover the source of the Nile ?' Of course Oswald knows quite well that the source of the real live Egyptian Nile is no longer buried in that mysteriousness where it lurked undisturbed for such a long time.

But he was not going to say so.

It is a great thing to know when not to say things.
'Why not have it an Arctic expedition ?' said Dicky; 'then we could take an ice-axe, and live on blubber and things.