Original: It also contains one of the most striking examples of Ives' experimentalism: in the second movement, he instructs the pianist to use a  piece of wood to produce a dense but generally very soft cluster chord.
Simplified: It also has an interesting example of one of Ives' experiments: in the second movement, he tells the pianist to use a 14¾ in (37.5 cm) piece of wood to make a thick but soft  cluster chord.