The armonica consists of 28 hemispherical glass cups, each with an open neck or socket at its center. Each neck is fitted with a cork that has an opening through which an iron rod or axle can be passed. The bowls are arranged in order of descending size and thickness, along the iron rod. The rod is mounted horizontally within a frame, above a shallow tined iron tray or pan into which water can be poured. By dipping their hands into the water and rubbing them on the rims of the cups, a musician produces musical tones.

The mahogany frame of the instrument appears to be in the neoclassical style of the first quarter of the 19th century. A pair of upright rectangular pillars spread with a concave curve to a high, square-sided base joined by a flat wooden base. Mounted between is the vertical box or cabinet in which the instrument is housed. At the wide (viewer's left) end is a wheel housing for the wheel or gear (not visible) that spins the nest of glass cups. The wheel is concealed within a disk-shaped wooden cover. Mounted at the left side of the base is the mechanism for turning the set of bowls: a large disk or flywheel foot treadle on the floor of the base, a tape running from the end of the treadle to a long, slender, wooden paddle. The treadle has a leather hinge.

Mounted on each end of the instrument is a large brass bail handle for moving the object.

There is a curved wooden cover hinged the width of the row of glasses.