Upon the Direction in which the North Magnetic Pole has moved during the last two Centuries

Abstract

IN an article upon Terrestrial Magnetism in the current number of the Edinburgh Review, referring to the fact that the compass-needle does not now in England point due north and south, and that it changes its position slightly from year to year, but that from our present ignorance of the source and laws of this change we cannot say that it will hereafter be as much in one direction as it has been in another, the writer remarks (p. 424): “Still the strictly progressive character of this change compels us to regard it as the expression of some determinate cause or causes. The question then arises, Where are these to be found? Now, from whatever point on the earth's surface we contemplate the phenomenon, we find ourselves in the presence of two distinct magnetic systems. This was first clearly recognised by Halley as a necessary consequence of even the scanty information at his command, and the accumulated observations of two hundred years have corroborated in a very remarkable manner the conclusions at which he arrived—that of these two systems one was fixed and the other in motion.”