In this past post and these comments, the subject of the glass (h)armonica came up. I'd never heard of it before. However, in the comments to this post, my mom posts a link to some good information.
In 1743 the Irishman Richard Pockridge constructed and performed on an ‘Angelic Organ’ (a set of tuned wine glasses) with a repertoire that included Handel’s Water Music.
Franklin was a prodigious inventor, and never became interested in anything without putting the whole force of his inventive genius to work.
So it’s no surprise that he devised an elegant design that simultaneously eliminated the water tuning (and the problem of constant evaporation), increased the playability and reduced the size of the instrument. Franklin called it the "armonica", after the Italian for "harmony." Working with London glassblower Charles James, he eliminated the water tuning by having each glass made with the correct size and thickness to give the desired pitch without being filled with any water, and made the set of glasses more compact and playable by nesting them inside each other, mounted on a spindle which was turned by a foot treadle.