midnight
When they came to the long , narrow lake on the lower reaches of the river , the sun was setting . They were all pretty much exhausted with the toil and excitement of the day . `` I vote we stop here , '' said Mac . `` There 'll be a moon toward midnight , and we can go on then . We ought to get some sleep . '' `` I 'm too hungry to sleep , '' said Fred . `` Well , so am I , '' Mac admitted .