EARTH TIDES.

Dominion, Volume 2, Issue 442, 26 February 1909, Page 7

EARTH TIDES.

; A: GERMAN PROFESSOR'S THEORY., (DI TSDEOBAFH— rBESS, ASSOCIATION— COPIItIOHT.) .. v : --'y ■■■■ :' ; ; Berlin, February;2s. : . Professor/ Hecker, .of Potsdam Observatory, as the result of: six years' observations, olaims' to have measured the.; diurnal oscillations of the. solid earth, 'which, he-, considers analogous : tq the-tides: of .the ocean. Be states that, there is a rise7and-fall each day'in the-surface of the earth of eight , inches. Sin George Darwin and; the.Emberley. 'Observatory 'confirm the. discovery, though the latter doubts the .tpial analogy.

; v 'VALUE.OF Vv. ■;:.;;--. (Rec v February;26j,o.4o,a.m.); r '.'y. v . ■'■.■'' . :■.- . Melbourne^-rebrnary 25.; Mr. Barachi, the (Elovernnient'.Astronomer, Inferring to. Professor Heoker'a ; discovery, said Professor Hecker was at ;one f -'time in Australia taking observations, in. the .Pacific to. determine questions relative, to variations in gravity. Professor Hecker : informed him. that the'instrument he;had made had. been : in,position since 1002. Acciirato. records,of the minutest. variations had been obtained by means of photography.;'. Mr. : Barachi said .such",.: discoveries; as Professor -Hecker's may have a most profound bearing upon our know- ; : ledge: regarding .earthquajjes 7 . and l ' possibly ■enable:-; scientists ..to anticipate dreadful calamities..'...■' :"' '? ' ,; : ■■■;' /; :; :-'[ : '.-': '■.

■LORD INVESTIGATIONS^.: : No solid matter possesses the, property of absolute'rigidity, and it has, therefore,- been admitted that: the existence, of tidal elastic deformation of the solid earth is.possible. ';ioTd Kelvin's : inTe3tigaticri's on .'this 'point— : the v state of strain.oii au elastic sphere under, stressled to;the deduction'that.if,an ocean be"superimposed on tho globe,: and tho"globe .rises:and fftlla witli the tide as though it (the globe) were fluid,,there will obviously be no tide .visible to an observer carried up and down ''with- the solid. Kelvin concluded, that, the ea'rta'a ;jnass .must have an effective rigidity at least us great aS'.thnt of steel. V If it were: true .that 'the :earth is a fluid ball/coated with a criist, : that crust must be of fabulous rigidity to resist the tidal surgings of the;subjacent .fluid. :,:-'-: : : • .In another investigation ;it has been: shown : that, local, elastic yielding., on lines of jiontinents may produce, an augmentation of apparent, tide in-.- certain, places on' account of the,flexure of the upper stratai when'a great weight; of; water is. added or subtracted from the adjacent-oceanic, area at high and, low" tide. There, isVreaspn to believe th'at.such'-flexuro !Uas' actually,been observed liy a delicate level on the coast of the Bay of Biscay. .:.-• .■.'-■■.