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No. 22: Jul-Aug 1982

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Where did the 1780 eclipse go?

October 27, 1780. The Maine Coast. An expedition from Harvard and the American Academy of Arts and Sciences, led by Samuel Williams, had set up equipment to observe the predicted total eclipse of the sun. A solar eclipse occurred all right, but the expedition was shocked to find itself outside the path of totality. They saw a thin arc of the sun instead of its complete obscuration by the moon. Modern analyses of this embarrassing incident for embryonic American science blame Williams for miscalculating the path of totality.

Actually, recent computations compound the mystery. The expedition measured the time of the eclipse as 40 seconds later than it should have been for their (erroneously selected) site. Modern analysts insist further that the expedition should have seen an arc 10 arcsec wide subtending an angle of 89; instead, Williams and his colleagues measured an arc of less than 24. Finally, the measured duration of the eclipse was far different from what it should have been.

The members of the expedition were skilled and their instruments excellent. What happened? Was it human error? Are modern eclipse-calculating methods in error? Did something astronomical happen, such as a temporary, slight glitch in the earth's period of rotation? The mystery persists.

(Rothschild, Robert F.; "Where Did the 1780 Eclipse Go?" Sky and Telescope, 63:558, 1982.)

From Science Frontiers #22, JUL-AUG 1982. 1982-2000 William R. Corliss

Science Frontiers Sourcebook Project Reviewed in:


  • "A sourcebook of unexplained phenomena is therefore a valuable addition to a collection of scientific literature. William R. Corliss has provided this in the past with his source books of scientific anomalies in several subjects, and now he has provided it for astronomy. He has done an excellent job of collecting and editing a large amount of material, taken in part from scientific journals and in part from scientific reporting in the popular or semi-scientific press." -- "The Mysterious Universe: A Handbook of Astronomical Anomalies", reviwed by Thomas Gold, Cornell University, in Icarus, vol.41, 1980

  • "An interesting, systematic presentation of unusual weather [..] This book is recommended for a general audience" --"Corliss, William R., Tornados, Dark Days, Anomalous Precipitation, and Related Weather Phenomena, Sourcebook Project, 1983.", revieweed in Choice, September 1983
  • "..the science is necessarily somewhat speculative, but Corliss's symthesis is based on reputable sources." -- "Corliss, William R. (Compiler). Lightning, Auroras, Nocturnal Lights, and Related Luminous Phenomena" reviwed by Joseph M. Moran, Univ. of Wisconsin in Science Books and Films, Sep/Oct 1983

  • "Before opening the book, I set certain standards that a volume which treads into dangerous grounds grounds like this must meet. The author scrupulously met, or even exceeded those standards. Each phenomenon is exhaustively documented, with references to scientific journals [..] and extensive quotations" -- "Book Review: The moon and planets: a catalog of astronomical anomalies", The Sourcebook Project, 1985., Corliss, W. R., Journal of the Royal Astronomical Society of Canada, Vol. 81, no. 1 (1987), p. 24., 02/1987