midnight
`` I 'm going to Chimney rock , '' he said to the boys . `` I should like to have one of you with me , but two ought to remain here . I 'm going to take some rockets with me . If I do not return before midnight , one of you advance along the summit to the south , provided with rockets . If one of my rockets is seen , the watcher must send one up to notify the boy in camp . Then both must make a run for Chimney rock , traveling so as to come upon it from the up-hill side . Is that clear ? ''