Six o'clock
`` You never can see through smoke very well , '' suggested Jo . `` True , '' laughed the professor , `` but still somehow I do n't like it . '' `` Then we saw a ship in the distance , apparently headed for this island , but far off the southern shore . '' `` Six o'clock , '' broke in Tom , as four bells were struck . `` I think I will accept the invitation to dine . '' `` A good plan , '' commended the professor , `` and Monday we must get an early start and learn , if we can about that ship you saw , and begin a more thorough exploration . '' `` I think so , too , '' replied Tom .