LIVING ON A MAGNET.

New Zealand Graphic, Volume X, Issue 27, 8 July 1893, Page 637

LIVING ON A MAGNET.

That the earth is a great magnet is a proposition that has become familiar to most readers of popular scientific literature. But it would be a great mistake to suppose that the origin of the earth’s magnetic condition, or the laws of its manifestations, are completely understood by men of science. In truth, among the most puzzling questions that science has yet to solve are those relating to the magnetism of the earth. The single fact that the North magnetic pole toward which the needle of the compass points is not fixed in position, but appears to rotate slowly around the geographical pole,—the pole of the axis on which the earth turns, —is in itself a great source of speculation. A theory recently put forth by Mr Henry Wilde, of England, to account for this and other peculiarities of the earth’s magnetism is just now atttracting attention, and, whatever else may be thought of it, is highly interesting, not to say startling. Mr Wilde believes that the interior of the earth is in a fluid condition, and that the inner fluid sphere rotates around a different axis from that of the outer solid shell. Everybody knows that the axis of the earth is inclined about twenty three and one-half degrees from a perpendicular to the ecliptic. But according to Mr Wilde the axis of the inner sphere is just perpendicular to the ecliptic, and he conjectures that the earth’s outer shell got skewed around twenty-three and one half degrees at a remote period in the past when, being yet in a plastic condition from heat, the mass of matter which now forms the moon was whirled off from it. The inner sphere he supposes to be in an electrodynamic condition, as all hot masses resembling the sun appear to be, while the solid shell is permanently magnetized. This curious theory would not get much of a hearing but for the fact that Mr Wilde has constructed a model which he calls a magnetarium, and which consists of a sphere rotating inside of the shell of a common terrestrial globe, a system of electro mechanism being provided which produces the proper magnetic conditions, and the axes of the two spheres being inclined to one another at the angle of twentythree and one-half degrees. With this ingenious contrivance he has succeeded in reproducing all of the peculiarities of the magnetic currents observed on the surface of the earth. He has even corroborated some curious observations that Columbus made on the direction of the magnetic needle during his first voyage in search of the New World, by producing on the model of the earth the magnetic conditions which prevailed on the actual earth in 1492 Whatever the result of Mr Wilde’s speculations and experiments may be, there is certainly a splendid field for discovery awaiting any person who earnestly undertakes to solve the many mysteries that yet remain about the colossal magnet on whose surface we dwell.