The same idea occurred to each of them.

They were only a few feet from the surface of the stream.

They were both good swimmers.

A plunge would give them their liberty; and once they had reached the river, how could Robur get them back again?
For his propellers to work, he must keep at least six feet above the ground.
In a moment all the chances pro and con were run over in their heads.
In a moment they were considered, and the prisoners rushed to throw themselves overboard, when several pairs of hands seized them by the shoulders.
They had been watched; and flight was utterly impossible.
This time they did not yield without resisting.

They tried to throw off those who held them.