Mathematical Geography

True geographic concepts are not composed entirely of plains, mountains, oceans, and other attributes of the earth's surface; the sun in its differing relations to the earth plays a most important part in the formation of such concepts. The difference in the winter and summer aspects of temperate North America, for example, would be appreciated with difficulty by an untraveled inhabitant of lowland equatorial tropics, inured to the monotony which results from a uniform twelve-hour