to the value of the crop. On the other hand a moderate de gree of thoroness of cultivation is necessary to get any results worth while ; and, besides, if a small crop is raised, the value of most of the uses of the land for that season would be en tirely thrown away. Only 5 or 10 bushels per acre might be raised with less expense per bushel merely for labor and ma terial, but there would be left no remainder to apply to the value of the land-uses. Between the wastefully small crop of 1 bushel and the wastefully large crop of 100 bushels an acre, there lies a point, more or less correctly ascertained by experience, where the largest net result is obtained, a point where by aiming to raise either less or more the man in charge gets a smaller net return (surplus of total price over ex penses).
§ 11. Intensive use of ground space. The principle of proportionality applies to ground-space in all industries. Some space is needed for any activity, even for mere existence, and a limited area cannot afford an unlimited number of uses. If a large library is accumulated in one small room, a point is reached where there is scarcely room to stand, and much energy is wasted in trying to find the books. In a university the psychical product, education, may be limited by the need of space. School-rooms, laboratories, and college class-rooms, if used all day and all night, would accommodate several times as many students as they do; but the "wee sma' hours" would not be popular; and, therefore, as students increase, buildings must be added. One cannot conveniently increase the business of a lumber-yard without a larger yard-space, or of a factory without a larger floor-space. But the added space may be gotten by spreading horizontally or piling up vertically. Even in agriculture vertical addition is pos sible by the use of greenhouses in which mushrooms are grown below the tables and tomatoes above, and where arti ficial heat gives a more intensive utilization throughout the winter. Therefore, with more space and also more time a single foot of ground can be made to yield half a dozen crops in the year. In the production of food, however, 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. In mercantile, commercial, and manufacturing businesses 10 acres or 60 acres of usable floor-space may be had by putting a building of that number of stories upon an acre of land, and installing elevators and moving stairways, parcel carriers, and telephones. Not only is the initial cost high, but the cost of maintenance likewise, and it is economically warranted only when land-space is very high priced. Business adapts itself to this law, but does not escape its operation. Neither the law of gravitation nor the principle (or law) of propor tionality 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.
§ 12. Intensive use of tools and implements. All the im plements used in agriculture are subject to the limitation of the principle of proportionality. Why will not one hoe, one
rake, one plow, one scythe, one horse, one wagon, do for all the farmers of a neighborhood I It might, in many cases, but it would be with much labor and time in carrying the things back and forth and in waiting for others to get through using them; it would require work to be continued all night, on Sundays and on holidays, and even then the plowing, hoe ing, harvesting, and other farm operations could not be per formed when most needed. Even now there is much loss in just these ways because, tho every farmer has at least one, and some have many, of these tools, there are brief periods when there are not tools enough. Why, then, not have more tools t Because they cost. Between the extremes of no tools and a multitude a balance is struck at a point where the last additional tool adds to the price of the crop at least as much as the tool costs. The mode of estimating these costs we have later to study more closely.
In manufacture, whether by hand tools in small shops or by machinery, in transportation, whether by boat or railroad, there is, in the mind of the manager, the same ideal point of equilibrium between the price of the uses to be added and the price of the other agents (labor, tools, materials) that must be expended to secure the additional product. To do nothing with a tool, implement, machine, for the purpose of saving the things that would have to be used with it, is to lose the use of it.