As an undergrad student in 1956 I took a technical writing course from
Gorden Mills at The University of Texas.  He believed that we fledgling
scientists should learn to write by emulating the real scientists of
yesteryear.

Gorden dug up some of Benjamin Franklin's technical writings (in script,
no less!) for us to peruse, two of which I remember to this day.  The
first dealt with his experiments in coloring body odors (farts and the
like) by eating different kinds of food.  This captured our sophomoric
minds.  I won't dwell on this non-MMI subject except to say that I
believe Franklin's tongue was firmly implanted in his cheek on this
topic.  It was memorable.

The second subject was his lab notes on what became the glass
harmonica.  For domestic use he had purchased some china and crystal
that proved to be mechanically defective.  This motivated him to begin
looking for a non destructive test to allow identification of defects
in vitreous materials.

He was playing around with the vibrations created by standing waves in
glass structures in hopes that the flawed glass would sound different
from the glass without flaws.  He experimented with vibrations created
by friction between different materials and the top edge of a rotating
(on a potters wheel) drinking glass.  He could produce a clear resonant
sound with his clean wet finger against the glass.

He was taking violin lessons at the time and thought that the resonant
glass sound was a good compliment to the sound of the violin.  He felt
that a musical instrument was possible based on this resonance.  He cut
the stems off of several glasses and mounted them horizontally on a
rotating shaft suspended above a tray of water so that the glass was
constantly wetted by the water.  He could the repeatedly produce
resonant sounds with his finger applied to the top edge of the glass.
The story goes on and on from there.

So, based on Ben's own words, the invention of the glass harmonica
began as a non destructive testing experiment.  His muse sidetracked
him into creating a musical instrument based on his experimental
observations.  I believe that's why some people call the glass
harmonica a scientific musical instrument.

Bill Finch