Mutations

The 1 1/3' and 1 3/5' stops are easily confused. Here are two simple ways of distinguishing between them:

• A 1 1/3' pipe is half the length of a 2 2/3' pipe. Remember that halving of pipe length raises pitch by an octave. Hence, 1 1/3', like 2 2/3', is a fifth-sounding rank, whereas 1 3/5' is a third-sounding rank.
• The mutation that places 5 in the denominator (1 3/5') is NOT the fifth, but the THIRD-sounding rank. The one that places 3 in the denominator (1 1/3') is NOT the third, but the FIFTH-sounding rank.