Named the “Alleluia Organ” at the request of Mrs. Alfred S. Hale, the principle donor, Opus 57 has a tonal design based on organs already old in the time of J. S. Bach. These historic organs were conceived as instruments of two divisions only. The Pedal and the Great formed one division, and the Choir, or Positive, formed the other. It was customary at that time to play the bass part on the manuals instead of on the pedals. Opus 57 allows for both through the use of mechanical transmissions from the Great to the Pedal, opening interesting possibilities for the performance of early music, especially the music of France before and during Bach’s time. To aid in the performance of the French classic literature the Trumpet and Cremona are closely based on the work of François-Henri Cliquot, the last of the French classic builders. The Swell division is located above the console in Brustwerk position. The Pedal 16' reed is an independent stop.
This organ is the first in which C. B. Fisk made use of double-draw stops, which when pulled halfway enable one rank to play, and when drawn fully add a second rank. This system appears in many later organs.
The case is a single unit with a high, wide, shallow cabinet of catspaw-figured white oak with a mahogany keydesk built into the lower face and burnished tin pipes in the façade. The naturals are made of grenadil, the sharps and flats of ivory-topped rosewood, and the faces of the stop knobs are hand-engraved ivory.
This case design and layout were subsequently used in modified form in two other organs, Opus 62 at Ascension Memorial Church in Ipswich, Massachusetts and Opus 65 at Parish of the Epiphany in Winchester, Massachusetts.