midnight
The Professor explained that this arborvitæ was ordinarily found about glaciers , and in cool , dim fiords . Determined not to be robbed of their provisions again , Tad led a string through the loops made in tying the meats to the provision line . He carried one end of the string into his tent and when he turned in he tied the end to his wrist . Long after midnight he felt a jolt at his wrist that brought him to his feet in an instant . Another jolt followed . The boy slipped the twine from his wrist and hurried out . The night was not so dark but that he could make out objects distinctly .