Sentence:  Everywhere else his ideas lay or hung in visible form : his models , drawings , ten <WSD>foot</WSD> canvases in monochromes from his painting days , and underfoot a windfall of broken-backed books that looked as though their insides had been ransacked by a maniac . 
Meaning of the word marked with <WSD> tags:  a linear unit of length equal to 12 inches or a third of a yard