Jean-Antoine Nollet (1700–1770), a French physicist, contributed to the theory of sound when he showed in 1743 that sound travels in water. He saw electricity as a fluid, subtle enough to penetrate the densest of bodies. In 1746 he formulated his theory of simultaneous ‘affluences and effluences’ in which he assumed that bodies have two sets of pores in and out of which electrical effluvia might flow. He later had a dispute with Benjamin Franklin over the nature of electricity. Nollet wrote a volume’s worth of letters to Franklin denying the verity of his experiments. In 1746 he gathered about two hundred monks into a circle about a mile in circumference, with pieces of iron wire connecting them. He then discharged a battery of Leyden jars through the human chain and observed that each man reacted at substantially the same time to the electric shock, showing that the speed of electricity’s propagation was very high.
Figure 3.48: French physicist Jean-Antoine Nollet.
Jean-Daniel Colladon (1802–1893) conducted experiments on Lake Geneva in 1826 demonstrating that sound travelled over four times as fast in water as in air. In 1842, Colladon showed that one can guide light with a falling stream of water. He was studying the fluid dynamics of jets of water that were emitted horizontally in the air from a nozzle in a container. In performing demonstrations of these jets in a lecture hall, he noticed that his audience could not clearly see what was happening to the falling water. He then used a tube to collect and pipe sunlight to the lecture table. Te light was trapped by the total internal reflection of the tube until the water jet, upon which edge the light was incident at a glancing angle, broke up and carried the light in a curved flow. His experiments formed one of the core principles of modern-day fibre optics. He wrote, “I… managed to illuminate the interior of a stream [of water] in a dark space. I have discovered that this arrangement… offers in its results one of the most beautiful, and most curious, experiments that one can perform in a course on optics.”
Figure 3.49: Swiss physicist Jean-Daniel Colladon.
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Jacques Charles François Sturm (1803–1855) was a French mathematician who, in 1826, with the Swiss engineer Daniel Colladon (Figure 3.49), made the first accurate determination of the velocity of sound in water, and a year later he wrote a prize-winning essay on compressible fluids. In 1829 he presented the solution to the problem of determining the number of roots, on a given interval, of a real polynomial equation of arbitrary degree (Sturm’s theorem). Sturm found a complete solution to this problem, which had been open since the seventeenth century. In 1836 and 1837, Sturm and Liouville published a series of papers on second order linear ordinary differential operators, which began the subject now known as the Sturm-Liouville theory.
Figure 3.50: Sketch of Jacques Charles François Sturm.
Lord Rayleigh (1842–1919). His first researches were mainly mathematical, concerning optics and vibrating systems, but his later work ranged over almost the whole field of physics, sound and wave theory, electrodynamics, hydrodynamics and photography. Rayleigh was awarded the Nobel prize in Physics in 1904 for his work on gases. See Chapter 3.3 for his work on underwater air bubbles. One famous quote is, “Te history of science teaches only too plainly the lesson that no single method is absolutely to be relied upon, that sources of error lurk where they are least expected, and that they may escape the notice of the most experienced and conscientious worker.”
Horace Lamb (1849–1934), English mathematician and physicist, had James Maxwell and George Stokes as his academic advisors, so it is not a big surprise to learn that he worked on both Maxwell’s equations and on the theory of motions of fluids. In 1910 he published the book Te Dynamical Teory of Sound. Within geophysics, he is well known for the mathematical solution of Lamb’s problem, which deals with an acoustic point source in a medium consisting of two homogenous half-spaces. Tis work was later used by Press, Ewing and Tolstoy to study the motion of waves in a liquid layer superposed on a solid bottom. At a meeting of the British Association in London in 1932, he is reputed to have said, “I am an old man now, and when I die and go to Heaven there are two matters on which I hope for enlightenment. One is quantum electrodynamics and the other is the turbulent motion of fluids. And about the former I am really rather optimistic.” (Tabor 1989). A very similar quote, however, is also attributed to Heisenberg.
Figure 3.52: Horace Lamb.
Figure 3.51: John William Strutt, 3rd Baron Rayleigh.
Musée d’histoire des sciences de Genève
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