On a visit to England in 1761, Benjamin Franklin was impressed by Edmund Delaval’s playing on musical glasses—the rubbing of moistened fingertips around the rims of glasses tuned by adding or subtracting water. He was inspired to improve on the instrument by affixing glass bowls of graduated sizes concentrically around a horizontal metal spindle and rotating the apparatus with a crank attached to a treadle. This keyboard-like arrangement made chords and scales easily playable. Franklin’s glass armonica (later dubbed “harmonica”) received later modifications, some unsuccessful—such as the use of a kind of violin bow or keyboard mechanism to activate the sound—but others were worthwhile, such as the extension of the instrument’s range by German maker Joseph Aloys Schmittbaur. Performances across Europe by Schmittbaur’s student Marianne Kirchgässner (1769–1808), blind from the age of four, brought the instrument to the peak of its popularity.

Kirchgässner’s playing in Vienna in 1791 inspired Mozart to compose his Adagio for solo glass armonica and also the Adagio and Rondo, K. 617, for glass armonica, flute, oboe, viola, and cello, which he dated May 23. She gave the quintet’s first performance with Mozart himself—probably on the viola part—at Vienna’s Kärntnerthortheater on August 19, and performed both pieces many times thereafter. Despite the fact that she died from a chest infection, rumor had it that the cause of death was nerve deterioration caused by the instrument’s piercing vibrations. The overall volume of the glass armonica, however, is relatively soft, and a critique of a performance she gave in London complained that her part couldn’t be heard above the other instruments. Whether the volume of the glass armonica was at issue, or there was simply a desire for wider circulation, a version with piano came into use even in Mozart’s day.

In the present performance, Friedrich Heinrich Kern plays the verrophone, a modern version of the glass harmonica using tuned glass tubes, invented in 1983 by Sascha Reckert.

Thus it gives a contemporary presentation of the sound rather than a “period instrument” re-creation. Mr. Kern has made subtle modifications in Mozart’s score to accommodate the differences in playing technique between the two instruments. Because the verrophone can produce more volume than the glass harmonica, the instrument is perfectly suited for Mozart’s quintet—a captivating, rarely heard piece that turned out to be the last chamber work from the master’s pen.

The Adagio’s dramatic C minor outer sections alternate powerful chords with delicate ruminating passages. The contrast of the solemn and the ethereal brings to mind Mozart’s opera The Magic Flute, which he was composing contemporaneously. His turn to the major mode brings a graceful middle section that features a lovely keyboard melody interspersed with comments by the quartet. Throughout both movements Mozart takes special care to alternate the keyboard with the other instruments, making the London critic’s complaint seem querulous.

Mozart’s treatment of the deceptively simple main theme of the Rondo shows sophistication in its many decorative variants that keep the ear engaged. The form is also a masterful infusion of rondo and sonata form. Most striking are the intervening sections that use a descending chordal pattern—which also receives its share of variation—to launch some ravishing modulations.

© Jane Vial Jaffe