§ 36. The Five principal parts of our globe, America, Europe, Asia, Africa and Australia are not equally thickly settled. Europe and Asia have, in proportion to their extent, the greatest population; America and Australia the least.—The following Plate, No. XV, shows the comparative population of these continents. Fig. I represents the whole surface of land on our globe, inhabited by nearly One Thousand Millions (One Billion) human beings. If these were to live throughout as close together as in _Europe_, then they would only occupy a surface of land as large in proportion, as the inner circle marked _a_. But the two rings, _b_ and _c_, occupy each as much surface as the circle _a_; hence there is yet room for twice as many human beings; before each quarter of the world is as thickly settled as Europe. Fig. II represents _Asia_ and its population. If this quarter were settled as thickly as Europe is, then its inhabitants would only fill the inner circle marked _b_; the ring _a_, therefore, is still left for settlement. Fig. III exhibits the population of Africa. If the inhabitants of this continent lived as close together as those of Europe, they would only fill the inner circle, marked _c_, and the surrounding ring might yet be inhabited. Fig. IV shows the comparative population of America. Its inhabitants, crowded together as the inhabitants of Europe, would only occupy the small circle _e_; the whole broad ring _f_, therefore, is still left for settlement!! Fig. V represents Australia. Its inhabitants, settled as in Europe, would only fill the circle _a_. Fig. VI represents the population of Europe filling the whole of that Quarter. The whole of these Six figures may represent to the pupil the comparative extents of the five great continents of our globe; but the _inner circles_ of these figures, and the whole of the sixth figure, show their comparative populations. From a close inspection of this plate the pupil may learn: 1. That the population of Asia is yet greater than that of all the rest of the world. (The circle _b_ in figure II being yet larger than the inner circles of all the other figures, and figure VI taken together.) 2. That the population of Europe is as yet larger than that of America, Africa and Australia, taken together. 3. That the population of Africa is larger than the joint populations of America and Australia. 4. That America if once settled as Europe is, will have more than Six times her population. [The teacher, if he think proper to ask the pupils some questions in reference to the Appendix, will find no difficulty in adapting them to the capacity of his pupils.] TABLE I. _Showing the Diameter, Surface, and Cubic Contents of the Sun and the Planets._