Sentence:  Red Gilbat was nutty....When the gong rang at the ball grounds there were ten chances to one that Red would not be present. He had been discovered with small boys peeping through <WSD>knotholes</WSD> at the vacant left field he was supposed to inhabit during play. 
Meaning of the word marked with <WSD> tags:  In a piece of lumber, a void left by a knot in the wood; such holes are often convenient for peering through when they occur in fences.