Today, how did people measure sound in the nineteenth
century? 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.
A nineteenth-century American
professor named Le Conte went to an evening gathering. It
was a typical lamplit musical party -- a regular kind of
social event in the Victorian age. He wrote about it in
the 1858 Philosophical Magazine:
Soon after the music began, I observed that the flame
exhibited pulsations that were exactly synchronous with
the audible beats. This ... phenomenon was very striking,
[especially] when the strong notes of the 'cello came in.
It was exceedingly interesting ... how perfectly even the
trills ... were reflected on the sheet of flame.
Today our fancy systems for recording and replaying sound
are so woven into the fabric of our times that we can
hardly picture a world without them. When Le Conte went
to that party, we had only the barest means for analyzing
or capturing sound. It was with his mind divided between
music and physics that Le Conte recognized a new way we
might get at the structure of sound.
Soon after, the Irish physicist John Tyndall showed us
all a special genius for that kind of observation. He
seized upon Le Conte's idea. Tyndall, born in 1820, had
started out as an engineer designing railway equipment.
He'd eventually gone to Berlin to earn a doctorate in
natural philosophy. He came back to London to teach at
the Royal Institute. And there he did important formative
work in sound, light, heat, electricity, bacteriology,
glaciology -- what am I forgetting? His ability was
astonishing.
But Tyndall's book on sound reveals his genius as clearly
as anything he wrote. It shimmers with highly-honed
mechanical means for displaying sound. He develops Le
Conte's observation into an eighteen-page section called
"Sensitive Naked Flames." He uses flames to measure pitch
and tone quality. At one point he stands across the room
from a flame and reads to it from a poem by Spenser:
Sweet words like dropping honey she did shed,
And through the pearls and rubies softly brake
A silver sound, which heavenly music seemed to make.
As the words touch the flame, it dances to all the
different vowel sounds.
He goes on to reflect light from tuning forks onto moving
paper. He gazes at effects of sound on water jets and
shallow sand. There is no end to his means. And they're
all so direct and palpable. I finally close Tyndall's
book -- this wild intermingling of music, phenomena, and
poetry -- and I come back to the hi-tech microphone now
just four inches beyond my nose.
Suddenly I'm back amid the twentieth-century spawn of Le
Conte's and Tyndall's work. Yet it would be a mistake to
come all the way back. We cannot afford to forget that
this world was built upon Tyndall's intimate interweaving
of our minds and our senses.
I'm John Lienhard, at the University of Houston, where
we're interested in the way inventive minds work.
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