midnight exactly
`` I propose , general , that I should conceal myself somewhere on the face of the heights . I will spread a handkerchief against a rock or tree , so that it will not be seen either from above or below , but will be visible from the ships in the river . I can not say , of course , whether it will be near Cap Rouge or Quebec ; but , if you will have a sharp lookout kept through a glass , as the ships drift up and down , you are sure to see it , and can let me know that you do so by dipping the ensign . At night I will make my way down to the shore , and if , at midnight exactly , you will send a boat for me , I shall be ready to swim off to her , when they show a lantern as they approach the shore . Of course , I can not say on what day I may be in a position to show the signal , but at , any rate , if a week passes without your seeing it , you will know that I have failed to make my escape , or that I have been killed after getting out . '' Chapter 19 : A Dangerous Expedition . The details of the proposed expedition being thus arranged , the captain left the cabin with James , and the latter paced to and fro on the quarterdeck , while the captain sent for the boatswain and directed him to pick out four men who could swim well , and who were ready to volunteer for desperate service .