nine o'clock
`` But I think we 'd better keep one fellow on guard when the rest go to bed . The guard can take a two hour trick . He can keep the fire going , and , if anything happens , he can warn the other fellows in turn . '' So , at nine o'clock , when the others turned in , Greg , the air rifle in one hand , paced softly up and down the cabin , watching , listening . But nothing happened during Greg 's watch . At eleven he called Tom Reade to relieve him . Just before midnight the same wailings as on the night before started in again .