Sentence:  The Rochdale climber spoken of once fell 70 feet from a mill at Linfitts, owing to an accident while he was <WSD>laddering</WSD>. He was terribly hurt, but recovered, and still carries on his trade with unshaken nerve. 
Meaning of the word marked with <WSD> tags:  To ascend (a building, a wall, etc.) using a ladder.