WORLD SLOWS DOWN

King Country Chronicle, Volume XXXIII, Issue 4815, 26 July 1939, Page 2

WORLD SLOWS DOWN

__ o EFFECT OF TIDES IN NARROW SEAS. A day 47 times the length of our day was predicted by the Astronomer Royal, Dr. Harold Spencer Jones, in the Halley Lecture in the Oxford University Museum, reports the

London Times. His subject was "The Earth as a Clock," and he described the installation at Greenwich of a new quartz clock which it was hoped would be a better timekeeper than the earth. He referred also to the exceptional strength of the currents in the Irish Sea which played so large a part in the Thetis disaster. It was found in 1920 by Professor G. L. Taylor that there was an unexpected slowing down of the earth's rotation through the large dissipation of energy as a result of tidal friction in enclosed narrow seas where the tidal currents were strong. Professor Taylor investigated in detail the Irish Sea, where the strength of the currents had been demonstrated in the tragedy of the Thetis, and found that the dissipation of energy in the Irish Sea alone was many times greater

than in all of the open oceans of the world. This investigation was extended by Dr. Jefferys to other enclosed seas, and he was able to establish that tidal friction in such seas would account quantitatively for the observed slowing down of the earth's rotation. This slowing down was small in amount, the length of a day increasing in the course of a century by a little more than than two-thousandths of a second, but the effect was cumulative over long periods of time. The length of the day would continue to increase until it was equal to about 47 of our present days, when the earth would always turn the same face to the moon just as the moon always turned the same face toward the earth.