midnight
Exhausted as the boys were , they knew that one of them would have to stand watch to see that the foxes did not gnaw their way out of the cage , and that the trappers did not attack the camp . They drew lots for it ; Macgregor selected the short straw and Fred the long one , and they arranged that Mac should take the watch for two hours , then Horace , and lastly Fred . The mosquitoes were bad , and there were no blankets , but Fred seemed to go to sleep the moment he lay down on the earth . He did not hear Horace and Mac change guard at midnight , and it seemed to him that he had scarcely done more than close his eyes when some one shook him by the arm . `` Wake up ! It 's your turn to watch ! '' Horace was saying .