STRUCTURE OF EARTH

Wanganui Chronicle, Volume 79, Issue 19, 23 January 1935, Page 10

STRUCTURE OF EARTH

MF.GI.BCTF.D EXPERIMENT. I h-e “ magnetarium ” of Dr. Wilde, a nieclutnica.l model of the cartlh eon >tructed over Io years ago ami since | neglected by scientists, was the subject I of a paper rend to l.he Manchester! IlJlerarv and Philosophic:!! Society by |i >r. ,1. K. \shworth and Dr. W. B. I Wright. Phc authors claimed that 1 'though the K.oyal Society did not pub I li-ih the results Wilde submitted to | them, sU'bsequenit research had justified I hi> m-ost imporj.ant conclusions. i I’hv magnetarium has recently come I into I he possession of the Literary and I I’liiloso'p-hical Society, st-ates the ManI Chester Guardian. It consists of a ispheric-al shell lined internally with | windings of wire, and of a core, con centric wilh the shell, on which there jure other windings of wire. KlCcti’ic currents, when passed through these wires, create magnetic, fields, and it in I Idle object of the model to shcrw how [the mtignelism of the. earlh ran in this iwav be imitated. It was designed, '-aid fir. Vshwurlh. I<j satisfy certain j postulates. The lirst was that the [earth was at uuc time a primeval

sphere of incandescent gases revolvitq on an axis at right-Augles to the plam of its orbit, and that it was symmetrically electro-dynamic, so that a com-pass-needle would point due north and .south on every meridian. The pecond was tdiat. this sphere in course of cooling became surrounded wit’h a shell of liquid or solid matter, capable of retaining magnetism, with its polar axis tilted over about its centre, but leaving the plane of rota-fiiou of the internal gaseous sphere unaltered. The third was that the internal sphere rotated more slowly thau the external shell. The outstanding achievement of the model am] the element of novelty in Wilde’s experiment was, in fact, the conclusion that the floors of the oceans had a. composition essentially different from that of the continents and contained considerably more iron and other magnetic substances. Dr. Wright, supported Dr. Ashworth’s argument with evidence derived from a. study of the rock structure of oceanic islands. The rocks in these islands, be sai'l, were bas»alts, having a heavy routeut of iron. Recent gravity ineaI surements onrthe ocean had also shown I that the ocean beds themselves were heavy in comparison with the. conI tinents. He outlined the oftkes of siliceous matter on the baMlt | which formed the ocean beds.