But he was too late.  One moment the Chinaman crouched, limp and helpless, in the bottom of the boat forward, with his hands hidden in his wet sleeves, the next he had made a frog-like leap at the coxswain, driven a sharp knife in the muscles of his back, and leaped overboard. Not into safety, though; for one of the men stood ready, and, as the wretch rose, brought down the blade of his oar with a tremendous chop across the head, and the pirate went down to rise no more.