_General Differences between the Condition of Densely Peopled Regions and that of Sparsely Peopled Ones._--In a very general way it may be said that the comparative amount of manufacturing should naturally vary directly with density of population, and that the comparative amount of agriculture should vary inversely to it. In computing density due regard must, as has been indicated, be paid to the quality of the land as well as the area, since a number of inhabitants which would unduly congest a sterile agricultural region can be well maintained on a fertile one. In the accompanying figure the line _AD_ inclosed by the vertical lines represents the part of the earth which we have called central, and the left side of it is the part of this area which has the sparsest population, while the right side is that which has the densest. The rising line _BC_ represents the varying density of the population in different parts of the broad area we regard as general economic society, the dotted line _EF_ may be taken as expressing the increase in the part of the labor and capital of the country devoted to manufacturing as population becomes denser, _AE_ measures the proportionate number of persons engaged in manufacturing in the region of sparsest population, and _DF_ measures the comparative number in the region most densely peopled. [Illustration] _AG_ and _DH_ represent the numbers engaged in agriculture in the two regions, and the descent of the line _GH_ represents the predominance of agriculture in the sparsely populated part and the subordination of it in the part that is densely populated. If we assume that capital in the different types of employment varies as does labor, the descent of this line toward the right means a decline in the fraction of the whole force of labor and of the whole fund of capital devoted to cultivating the soil; while the upward trend of _EF_ means the enlarging proportion of labor and capital devoted to manufacturing as we pass from a region of sparse population to regions more and more crowded. The wavy character of the two dotted lines is designed to express the fact that local conditions other than mere density of population favor the one type of occupation rather than the other; and moreover, nothing in the figure is intended to mean that the increase in manufacturing and the comparative decrease in tillage from the left of the diagram to the right are in any exact numerical proportion to the increase in the density of population. The figure as a whole rudely represents the fact that an approximation to the static distribution of population insures an approximation to a static apportionment of occupations within the described area and indicates the general nature of that apportionment.