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main point of difference between the two hemispheres is that, as the sun now culminates in the north, its apparent motion is not in the direction of the hands of a watch, as with us, but in the opposite direction. In middle southern latitudes, the northern constellations, so familiar to us, are always below the horizon, but we see new ones in the south. Some of these are noted for their beauty, the Southern Cross, for example. Indeed, it has often been thought that the southern heavens were more brilliant and contained more stars than the northern ones. But this view is now found to be incorrect. Careful study and counts of the stars show the number to be about the same in one hemisphere as in the other. Probably the impression we have mentioned arose from the superior clearness of the sky in the southern regions. For some reason, perhaps because of the drier climate, the air is less filled with smoke and haze in the southern portions of the African and American continents than it is in our northern regions.

What we have said of the diurnal motion of the northern stars round and round the pole, applies to the stars in the southern heavens. But there is no southern pole star, and therefore nothing to distinguish the position of the southern celestial pole. The latter has a number of small stars around it, but they are no thicker than in any other region of the sky. Of course, the southern hemisphere has its circle of perpetual apparition, which is larger the farther south we travel. That is to say, the stars in a certain circle around the south celestial pole never set, but simply revolve around it,