They were whirling down a raging river in a cart.

In a few moments it was probable that the cart would upset, and then---- Presently the wheel bumped against something, the cart gave a great lurch, and scraped along a little.
"Now for it," thought John, for the water was pouring over the flooring.
Then came a check, and the cart leant still farther to one side.
_Crack!_ The pole had gone, and the cart swung round bows, or rather box, on to the stream.

What had happened was this: they had drifted across a rock that projected from the bed of the river, the force of the current having washed the dead horses to the one side of it and the cart to the other.

Consequently they were anchored to the rock, as it were, the anchor being the dead horses, and the cable the stout traces of untanned leather.

So long as these traces and the rest of the harness held, they were safe from drowning; but of course they did not know this.
Indeed, they knew nothing.