The Earth, a great magnet

When the invitation came to me to address this evening a lecture to a Liverpool audience in accordance with a usual custom during meetings of the British Association, the natural desire arose to select some subject which should have a more or less close relation to the industries and commerce of your great city. With a choice somewhat limited by the nature of my own studies, it seemed to me, however, that we might find an appropriate topic in discussing, for a brief hour, the fact of the earth's magnetic properties, and the history of the discoveries by which that supremely important knowledge has been gained. To do this with advantage, we shall approach the subject through the avenue of some experimental demonstrations intended to place you in possession of the elementary principles of magnetic science.