Abstract
SINCE the letters on the subject appeared in NATURE, the Reynolds line has been seen by readers both on fresh-water and sea-water. Some of those who have seen it, however, missed the note in the News and Views columns of the July 4 issue (p. 20), giving references extending back to a paper by Prof. Osborne Reynolds. Mr. K. G. Denbigh, of Draidland, Norton Road, Norton-on-Tees, Durham, has sent an account of his observations. He saw the line at the fort of Carrawburgh, where a spring rises in a circular pool about five feet deep and eight feet in diameter. It formed a loop, roughly circular and about twelve inches across, surrounding the spot where the water rising from the bottom broke the surface. Apart from this small area where the water was perfectly clear, the pool was, no doubt, covered with a film; he refers to pollen grains and other small vegetable matter floating on it. As Reynolds explains in his paper, the line is only stationary if the rate of spreading of the film over the clean surface of the water is balanced by the outward motion of the water. Mr. Denbigh found that the loop was sensitive to wind, contracting to a point when disturbed and expanding again when the wind died down. He also noticed and sketched the distortion of reflections of reeds where they appeared to cross the line. He watched the line for nearly an hour, until a few soap shavings thrown into the water proved to be an overdose for this sensitive phenomenon.
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The Osborne Reynolds Ridge. Nature 138, 612 (1936). https://doi.org/10.1038/138612c0
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DOI: https://doi.org/10.1038/138612c0