No. 1386:
Franklin's Glass Armonica

Today, singing wine glasses. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

Ben Franklin writes to his friend Father Beccaria in Italy. Beccaria has sent a new study of electricity, and Franklin apologizes for having nothing to send back on the subject. "However," he says,

it may be agreeable to you, as you live in a musical country, to have an account of [a new] instrument that seems peculiarly adapted to Italian music, especially that of the soft and plaintive kind.

Franklin plunges into a four-and-a-half-page set of instructions for building this instrument. He begins by recalling an Irish inventor who once arranged wine glasses on a table and filled each to a different depth. Then he created tunes by rubbing their rims.

That trick has often been done. You may've seen it, but it's awkward. You can't play anything very rhythmical. Franklin wanted to create real music with rubbed glasses, so here's what he did:

He had a glass-blower make a set of glass hemispheres ranging in size. Each had a hub with a hole at the center. The glass tapered outward to the rim. He then ground each hemisphere until it played one pitch accurately. Next he mounted all the hemispheres along a three-foot spindle, from the lowest tone to the highest.

Now, how to play this Christmas tree of nested glass bowls? Franklin, of course, mechanized the process. He mounted a flywheel with an 18-pound lead rim on one end of the spindle, put the whole arrangement on a small table, and provided a foot-treadle to spin the flywheel and the glass bowls. The performer could now sit at the table, pedal the machine, and place his fingers on the rim of successive glass bowls to create a tune. But there's more. With Franklin, you can always look for more.

He color-coded the seven notes of the scale with the seven primary colors. The lowest note was a bass singer's low G, and it was blue; A was indigo, B purple, and so on up to a soprano high G. Franklin tells players to wash the glasses and their fingers thoroughly, then apply just a bit of chalk-dust to the fingers. He concludes by saying that the instrument's tones

... are incomparably sweet,
That they may be swelled or softened at pleasure,
[that they may be] continued to any length [and]
that the instrument, being once well tuned, never again wants tuning.

Franklin fairly glows with pride in his accomplishment. He's as pleased with this as with his work on electricity or, later, the U.S. Constitution. He finishes his letter saying,

In honour of your musical language, I have borrowed from it the name of this instrument, calling it the armonica.

History has largely lost the details of Franklin's musical instrument and called it a glass harmonica, thus hopelessly confusing readers. But this was no mouth organ. It was a truly unique American invention, which a few people are at last taking up today, over two hundred years later.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)

Franklin, B., Experiments and Observations Made in America at Philadelphia ... 4th ed., London: Printed for David Henry; and sold by Francis Newbery, at the corner of St. Paul's Church Yard: MDCCLXIX. The letter to Father Giambatista Beccaria appears on pp. 427-433.

Also check the entries under Franklin, Benjamin, and Musical Glasses in The New Grove Dictionary of Music and Musicians. (Stanley Sadie, ed.) London: MacMillan Publishers Ltd. 1980.

Glass armonica player William Wilde Zeitler describes the instrument and its history in some detail in a new book: The Glass Armonica: The Music and the Madness

Note added, May 11, 2011, Jean Krchnak, UH Slide Librarian, provides this excellent video on the glass armonica:


For a copy of a page of Franklin's letter,
click on the thumbnail above.