Knowledge of scientific agriculture makes it possible to raise increased crops on a given area of land, but, as every farmer knows, the point comes when additional investment per acre does not pay.

The law of diminishing returns may also be proved by showing the absurdity of the contrary. For, if the law of diminishing returns were not true, enough potatoes to feed the whole world could be produced from a single acre of land by simply increasing the expenditure of labor and capital.

The Marginal Product of Labor and Capital.-In agriculture, as in all production of wealth, the farmer has the option of combining labor and capital as he thinks most advantageous. If labor is expensive, he will try to substitute machinery for part of the labor. The point which he must consider is whether additional labor earns its wages and whether additional machinery pays interest on the investment and provides for its renewal when worn out. If able, the farmer will continue to employ additional labor, until the point is reached when the laborer only produces enough to pay his wages. The laborer who just produces enough to pay his wages is called "the marginal laborer"; he is not necessarily the last laborer employed, but any laborer when the investment of labor, land, and capital has reached a certain point.

From a photograph by Publishers Photo Service

FARM LANDS IN NEW ENGLAND AND MONTANA

In New England the machinery used on a Western farm could not be employed. Do you wonder that wheat is produced cheaper in the West?

In the same way he will invest capital, if he can, until the point is reached when it just returns enough to make it pay; this point is that of the "marginal productivity" of capital.

Scientific Agriculture. No business requires greater knowledge than that of farming. A farmer, in order to make the most of his calling, must be something of a mechanic; must know much concerning the care of animals; must have some knowledge of such matters as the chemistry of the soil, fertilizers and their uses, rotation of crops, modes of fighting insects, fungus, and other pests; must be able to keep accounts and to attend to buying and marketing.

Scientific agriculture is that method of agriculture that enables the farmer to make the best use of his opportunities. The teaching of agriculture in schools and colleges and the published reports of the United States Department of Agriculture and state experiment stations, have done much to raise the standard of agriculture in the United States.

Urban and Country Population.-The table on next page shows the increase in the urban population of the United States since 1790, the year of the first census.

Decline in Rural Population. The relative decline in the rural population is partly explained by the fact that every labor-saving device suitable to agriculture diminishes the amount of labor necessary on the farm and increases the demand for labor in the city factories. Likewise all improvements in transportation tend to hurt business in the small villages by making it easy to get supplies from the cities.

* Population of places of 8,000 inhabitants or more at each census, except for 1920, 1910, and 1900, in which cases all places over 2,500 are included.

During the Great War the opportunities for employment at high wages in the cities drained the country of much of its agricultural labor. It is true that the lure of the city attracted many, but the economic argument doubtless had the most influence. The end of the war saw a return of many agricultural laborers to the country, but the scarcity of labor continues to be one of the great difficulties of American farmers.

The eight-hour day is less common on farms than in factories. During harvest season twelve hours usually constitute a day's work and ten hours in the winter. But there are compensations. The employer and the employee usually work together and a better understanding exists. between them than in factory work. The work is chiefly

out of doors and is not onerous for a man of good physical powers. It is probably true that ten or twelve hours in farm labor is not more exhausting than eight hours in a factory.

Size of Farms. In the United States most farms are small. There are many large farms, but the average farm in 1910 was 138 acres, while in 1850 it was 202 acres. As intensive farming becomes more common, the size of the average farm may be expected to decline.

The United States census authorities regard a "farm" as all the land which is directly farmed by one person, either by his own labor alone or with the assistance of members of his household or hired employees. When a landholder has one or more tenants, renters, croppers, or managers, the land operated by each is considered a "farm." In 1900 the number of farms in the United States was 5,737,372. In 1910 the number had increased to 6,361,502, an increase of 10.9 per cent during the decade. By 1920 the number had reached 6,449,998, but the increase during the last decade was only 1.4 per cent.

Marketing of Farm Products. The difference between the price of agricultural products at the farm and in the city retail markets has been a matter of comment for many years. As this chapter is being written, potatoes may be purchased from farmers in Suffolk County, Long Island, for $1.50 a bushel, while they are selling in Brooklyn, only sixty miles away, at $3.50 a bushel; the best green corn costs twenty-five cents a dozen at the farm in Suffolk County and sells at retail in Brooklyn at sixty cents. The usual method of marketing most farm products is to consign them to a commission merchant, who sells them