possible an increasing business in manufacture, trade, or commerce upon the same area of land. All industries, if looked at consistently from this standpoint, are subject to the same condition, though it is true this will make itself felt in varying degrees in different lines of industry. In agriculture some similar devices are possible by the use of greenhouses, but it is true that in it, on account of the need of sun, light, and air, the limits of space are more quickly felt, and are less elastic than in most other industries. The difference, however, is one of degree, and not of kind. Higher factories, larger stores, enable manufacturers to adapt themselves to the law as applied to the surface of land, but not to escape its operations. Neither the law of gravitation nor the law of diminishing returns is violated or broken when materials are lifted to build the upper stories. Both "laws" are at work, even when the building is rising from the ground. Men are merely adapting their conduct to the conditions imposed by gravitation and diminishing returns. [Sidenote: Confused with the question of large production] Manufactures usually are thought of as enlarging by increase of the amount of capital employed, without limitation as to the area covered. But even here a limit is reached in the amount of capital that can be employed at any one location because of the difficulty of widening the market. The question, however, is one of the advantages of large production with large capital, not of the increasing use of a limited area of land. If manufactures and agriculture are to be compared with reference to their economic nature, it is essential to clear thinking that both be looked at with reference to the same conditions, and from the same point of view. [Sidenote: Technical confused with historical diminishing returns] 4. _Technical diminishing returns are often confused with historical diminishing returns._ The principle of technical diminishing returns is that at any given moment the uses obtainable from any indirect agent cannot be indefinitely increased without increasing difficulty. Historical diminishing returns occur when, in fact, human effort is less bountifully rewarded in a later period than in an earlier one. If to-day a day's labor in agriculture produced less than fifty years ago, historical diminishing returns would have occurred. In fact, labor is more bountifully rewarded in agriculture than fifty years ago, yet it is true to-day that there are few fields or appliances which, if used more intensively with the prevailing prices of labor and material, would not show a diminishing return to the additional capital applied. Therefore, in the historical sense, increasing returns have prevailed, yet at every moment it has been necessary to apply resources under the guidance of the principle of diminishing returns. § III. DEVELOPMENT OF THE CONCEPT OF DIMINISHING RETURNS [Sidenote: Recognition of diminishing returns to land]