Show Tides Said Slowing Up lI F Planet Extending Day WASHINGTON Tides Tides raised by the moon in the earths earth's liquid core are arc slowing the planets planet's revolution and increasing the length of the day This thesis is advanced in a report prepared prep red for the official organ of the British association for the advancement ad of science by Dr W. W M. M Elsasser of the University of Pennsylvania i It long has been known that that the length of the day is increasing by bya a minute fraction of a second each year This generally has been at at- attributed attributed attributed to the frictional drag of tides in shallow seas the Bering sea alone accounting for almost half the effect However it also is known that the core of the earth is liquid in ina ina ina a strange form iron form iron at an enor enor- enormously enormously enormously i high temperature but un un- under un- un under der tremendous pressure But it would respond like water to the pull of the moon Dr Elsasser says These internal tides act like brakes on the earths earth's rotation he I explains This theory he says satisfies sat sat- satisfies the observed rates better than if the retardation were as as- ascribed ascribed I to t the h e drag of sea tides I 1 alone The Th theory assumes that the I core of the earth is rotating some somewhat some what more slowly than the shell and that there are arc areas of tidal turbulence turbulence lence essentially storms inside the earth The idea of drag due to inter internal internal nal tides receives support from fromI I time long-time records of changes in inthe inthe the earths earth's magnetism in local I areas recently published by the terrestrial magnetism department of the Carnegie Institution of Washington These indicate a dif different ferent rotation rate for the core and the crust and a gradual dis displacement displacement placement of the latter from East to West It is almost as if there were two rotating planets one in inside side ride fide the other e ei i |