These pages comprise a dictionary of terms relating to the pipe organ. Please keep definitions to a few sentences, and do not include pictures or sound clips. When more space is needed for a term, a new page can be created for it. Half-length [adjective] - used of resonators on reed pipes which are half the length usually required for their pitches. Done often to save space or money, and usually only in the bass octave, except in the case of fractional length reeds where half length creates a desired tonal characteristic. Halve Harmonic Bridge Harris, Renatus Haskell, William E. Hook, E. & G. G.