Colladon’s ‘light jet’ predates Tyndall’s ‘light pipe’
John Tyndall deserves credit for many things as a giant of 19th century science, but he was not the originator of the water-jet light-guiding experiment that is often cited as the inspiration for fiber optics.
John Tyndall deserves credit for many things as a giant of 19th century science, but he was not the originator of the water-jet light-guiding experiment that is often cited as the inspiration for fiber optics. (“Ireland invests millions in new Photonics Centre,” Optoelectronics Report, May 1, p. 3)
Tyndall first demonstrated light guiding a water jet at the Royal Institution in London on May 19, 1854, and described the demonstration in his popular books explaining science. However, Swiss physicist Daniel Colladon performed an identical light-jet experiment in Geneva in 1841, which he described the following year in the French journal Comptes Rendus.1 The late Norwegian engineer Kaye Weedon found the 1842 paper sometime before 1970, and described Colladon’s work in talks, but he did not publish anything and most later writers failed to notice it.
I corresponded with Weedon in the 1980s, and evidence I uncovered while writing my book City of Light: The Story of Fiber Optics (Oxford, 1999, paperback 2004), suggests that Colladon’s work indirectly inspired Tyndall. Tyndall’s original notes, preserved in manuscript form at the Royal Institution, apologize that the demonstration did not show “something entirely new.” He wrote that his mentor, Michael Faraday, suggested the water jet after another demonstration Tyndall had planned did not work as desired.
Circumstantial evidence suggests that Faraday saw a demonstration of Colladon’s water jet. Faraday was a close friend of Auguste de la Rive, a Swiss physicist who built his own version of Colladon’s water jet in 1841. Moreover, Faraday visited Switzerland in the summer of 1841, where de la Rive likely would have shown him the water jet demonstration.2 Faraday or Tyndall should have credited Colladon, but by 1854 Faraday’s memory was failing, and he probably had forgotten who had originated the water-jet experiment.
A century later, Narinder S. Kapany saw Tyndall’s account of light guiding in a water jet while writing his doctoral dissertation, and later cited it as the first such demonstration.3 His mistake was understandable, but it is still being repeated, despite the fact that Colladon clearly demonstrated light guiding in a water jet more than a dozen years earlier.
1. D. Colladon, “On the reflections of a ray of light inside a parabolic liquid stream,” Comptes Rendus 15, 800 (July-Dec. 1842).
2. L. Pearce Williams, Michael Faraday (Basic Books, New York, 1965), p. 358.
3. N.S. Kapany, “Fiber Optics,” Scientific American 203, 72 (November 1960).