Opus 78 was the largest organ built by the company during Charles Fisk’s lifetime, and at the time was the largest tracker organ built in this country in the twentieth century. An intentionally eclectic instrument, it incorporated ideas from the study of historic European organs and more recent lessons from the building of earlier Fisk organs. It was Charles Fisk’s talent to find a way for pipe scales from the Silbermann brothers to coexist with those based on the 17th century Stellwagen Brustwerk at the Jakobikirche in Lübeck. He included Gambas and Flûtes Harmoniques in the style of Cavaillé-Coll to make possible a true 19th century French Romantic sound, while in the Great, German reeds with leathered lead-faced shallots developed circa 1580 by the Scherers, stand side by side with 8' and 4' French reeds representing the 18th century influence of Dom Bedos de Celles. Much of the pipe work is hammered lead and some, including the façade, is 70% tin.

Reversible composition pedals included for ease of changing stops affect the Great Flue Chorus, the Great Reed Chorus, and the Swell Forte Stops. Other registration pedals include ventils to the Great windchest, the Pedal flues, and the Pedal Reeds similar to those found on French Romantic instruments. In 1992 a Kowalyshyn Servo-pneumatic lever was added to make key touch more sensitive when playing with the manuals coupled.

The oak casework includes gilded hand-carved pipe shades, most with a sea motif. Those in the Positive case were designed and executed by Morgan Faulds Pike of Gloucester, and those in the main case and the Pedal towers by Roger Martin of Rockport, Massachusetts.