AN UNSEEN ENEMY. 
53 
" Pretty soon I heard a squirrel chatter, and right 
afterward a bird sound, like this." 
Here Joe imitated pretty closely the long, plaintive 
whistle of the hermit thrush. 
"we started across the lake.'* 
The boys nodded to their father, to show that they 
recognized the notes ; and Joe gravely proceeded. 
" I knew then that something was out of the common, 
and that John apprehended danger; otherwise he would 
not have called me at all, or w^ould have sung out my 
name. The squirrel and the bird meant ' trouble — come 
