I knew why Mr Brooke required all his attention to be directed to the task he had on hand--very little reflection was necessary.  For it was a difficult task in that black darkness to follow the course of those two junks by sound, and keep doggedly at their heels, so as to make sure they did not escape.  And then once more the slow, careful steering was kept up, Mr Brooke's hand guiding mine from time to time, while now for the most part we steered to follow the distant whishing sound made by the wind in the junk's great matting-sails.