Why should this be? It must be due to the shape of the earth. The fact is, the earth would make a very bad golf ball. It is by no means of that perfection of symmetry which they say enables a golf ball to fly well and to run true on the putting greens. The earth is, in fact, not perfect as a sphere, either within or without. Its centre is not in the same place as the centre of its weight, and it is not round in shape. Everybody has heard that the earth is slightly flattened at the poles; but its irregularity goes much further than that. If we could strip it of its oceans, which fill up a good many of its imperfections, we should find its shape not that of a neat, round golf ball at all. The earth's actual shape without its oceans, its "geoid," as it is called, is that of a pear. The stalk of the pear is in the southern part of Australia, and contains Australasia and the Antarctic continent. This is surrounded on all sides but one (towards South America) by a sort of belt of depression in which the waters lie. That is the waist of the pear. This again is surrounded on all sides but one (towards the east of Japan) by a belt of elevation. That is the protuberant part of the pear, and here the great continental land areas rise. Finally, we find the nose of the pear in the central Atlantic, between the Madeiras and the Bermudas. Of course, the resemblance to a pear is not a very marked one. Our observer a thousand miles above the earth would not be able to perceive it, nor would the astronomers in the moon, if any astronomers existed there. But the earth is pear-shaped to a small extent nevertheless, and in the case of such an enormous mass a very slight deviation from rotundity will produce very great effects.