City of Light: The Story of Fiber Optics

GUIDING LIGHT AND LUMINOUS FOUNTAINS 23
oped a clear plastic that quickly replaced glass and quartz illuminators because
it is lighter, cheaper, more durable, and easier to bend. 37
The light-guiding effect that Colladon had conceived as a thing of beauty
was evolving into a useful technology with mundane applications. That would
have pleased Colladon, who took pride in his practical inventions such as
compressed air. He probably intended his paper in La Nature and his autobiography
to ensure that future generations recognized his pioneering role. Yet
he would have been furious to see the pioneers of fiber optics assigned the
credit for light guiding in a water jet not to him but to John Tyndall, who
first demonstrated it thirteen years after Colladon.
Professor Tyndall’s Performance
A small man with bright gray eyes, Tyndall joined the Royal Institution in
London in 1853. He quickly made a name for himself by giving informative
and entertaining talks in a long-running series of Friday evening lectures. 38
However, he found himself in trouble as time came for his talk on May 19,
1854. The demonstration he had planned wasn’t ready for the talk, and as
the deadline approached he talked with his mentor, Michael Faraday, who
had given similar talks for years. Faraday suggested he demonstrate the flow
of water jets and and how total internal reflection could guide the light along
the flowing liquid.
In his handwritten notes, Tyndall apologized for not showing ‘‘something
entirely new,’’ 39 but published accounts of the lecture omit that apology. He
used the water jet to conclude his lecture by demonstrating ‘‘the total reflexion
of light at the common surface of two media of different refractive indices’’—water
and air. Initially, the light emerged from a glass tube in the side
of a tank. Then he turned a valve so water could flow through the tube.
Thanks to total internal reflection, he wrote, the light ‘‘seemed to be washed
downward by the descending liquid, the latter being thereby caused to present
a beautiful illuminated appearance.’’ 40
It must have been a good show, and Tyndall made it part of his repertoire.
But he saw light guiding more as a parlor trick than a new scientific concept
and made no effort to properly attribute it to Faraday or anyone else in his
published account. Indeed, total internal reflection was a well-known phenomenon,
and Tyndall may have considered light guiding too obvious an
application to be new. However, Tyndall also probably didn’t know whose
idea it was.
Faraday was one of the greatest scientists of his time, but about 1840 his
memory started to fail him, a problem that slowly worsened over the years. 41
That fact that Tyndall didn’t credit him implies that Faraday remembered a
demonstration by someone else but that Faraday’s failing memory couldn’t
come up with the name and Tyndall didn’t want to embarrass him. It was a
common problem for Faraday by that time, especially on bad days. The name
Faraday forgot probably was Daniel Colladon.