Q:

what is meaning of " the water was hidden" in The Voyages of Doctor Dolittle story?

I am reading "The Voyages of Doctor Dolittle" story, I don't understand this sentence:

When they got round the bend in the river and the water was hidden
  from view, you could still see their huge brown sails towering over
  the roofs of the town, moving onward slowly—like some gentle giants
  that walked among the houses without noise.

Here what does "the water" mean? the river or the sea? How come to be hidden?
Thanks

A:

In this context, "the water" refers to the river.
The chapter starts by talking about the town on this river:

At that time Puddleby was only quite a small town. A river ran through
  the middle of it; and over this river there was a very old stone
  bridge, called Kingsbridge, which led you from the market-place on one
  side to the churchyard on the other.
Sailing-ships came up this river from the sea and anchored near the
  bridge. I used to go down and watch the sailors unloading the ships
  upon the river-wall.

The water is hidden by the bend in the river. In other words, there are things - trees, buildings, low hills - that are now blocking the view of that part of the river. But the ships in that part of the river have tall sails, and even though you can't see the river, you can see the tops of the sails. And as the ships move, you can see the tops of the sails move (probably towards the sea).

