The following description is a collection of Skinner's words regarding this stop, taken from The Composition of the Organ: The king of Flutes, the Flauto Mirabilis, was designed as a big voice for the Solo or fourth manual of large organs. [It] is an Harmonic Flute, preferably of wood, designed to develop a lyric brilliance. It blends with and matches in volume the Gamba and the Gamba Celeste, warms up the Tubas and, when used with the French Horn, abandons its character as a Flute and becoms a French Horn, thereby making an effective French Horn chorus. It has great power without the concomitant weight or �tubby� character too often found in large wood flutes. It has none of the thick, cloying characteristics of a Tibia or Philomela. The scale at tenor C is 4" x 3-1/4". The upper lip is highly arched. The cap rests upon an intermediate wedge shaped piece both inclined to direct the wind toward the upper lip. This is made necessary by the unusual height of the mouth, 1-3/4" at C. The pipes are of double length from C2 [2' C] up, giving the middle register greater brilliance than where the harmonics begin an octave higher. It cannot be developed to its most efficient point with less than a ten inch wind. Conspicuous examples of this voice may be found in the organs in the Cathedral of St. John the Divine, the National Cathedral in Washington, D.C. and others of similar magnitude. Maclean describes it as being tonally similar to the Grossflöte, Philomela and Melophone. Irwin describes it as follows: A Flute of open metal or wood, at 8' or 4' manual pitch, sounding with a tone of unusual loudness and brilliance, but not equal to the Stentorphone or some Tibia Plenas in power. Its large scale and low mouth cut-up give it clarity and penetration for either solo playing or ensemble use. The Latin word mirabilis means �wonderful� or �extraordinary�. Examples Osiris contains about 30 examples, about 2/3 of which are by Skinner or Aeolian-Skinner. All are at 8' pitch. The earliest examples are listed below. Flauto Mirabilis 8', Solo; Cathedral of St. John the Divine, New York City, New York, USA; Skinner 1910. Flauto Mirabilis 8', Solo; Trinity Episcopal Church, San Francisco, California, USA; Skinner 1925. Flauto Mirabilis 8', Solo; Princeton University Chapel, Princeton, New Jersey, USA; Skinner 1927. Sound Clips
Osiris contains about 30 examples, about 2/3 of which are by Skinner or Aeolian-Skinner. All are at 8' pitch. The earliest examples are listed below.