en in these charts seemed best to
suit the subjects treated. It is possible, however, that for all data
convenience would settle upon July 1, the beginning of the fiscal year in
the United States, as the best for beginning the universal statistical
year. Each chart in the series, of course, requires its particular
explanation.

The fluctuations of supply and prices for series of years are exhibited in
the Charts 4, 5, 6, 8, 9 and 12, and these are explained in detail at the
close of the chapter.

_Fluctuations with season._--Every product of the farm is known to have
conditions favorable or unfavorable from the mere changes of season
affecting the prospective supply. Conditions equally dependent upon the
seasons have something to do with demand. The result of both combined is
worthy of study by farmers and dealers in farm produce, that all may get
the full benefit of such knowledge as the study affords. For this purpose,
charts showing the annual fluctuations of staple products in the leading
markets have been carefully prepared. These may have a greater usefulness
than simply to illustrate the law of supply and demand, since it is within
the possibility of actual practice to in some degree modify by provident
foresight the extremes of fluctuation. It is hoped that the suggestiveness
of these charts may help the most enterprising farmers to adjust their
practice to conditions of market.

Charts Nos. 7, 10, 11 and 13 illustrate the fluctuations as related to
seasons.

_Law of diminishing returns._--In considering the value of farm products,
it is necessary to notice a natural tendency in all products of the earth
toward greater cost of effort in production. This is called the law of
diminishing returns, and is illustrated in every industry where the
accumulations of nature are depended upon for making labor effective.
Hunting, fishing and mining afford familiar illustrations of more work of
the same kind for equal product.

Agriculture, however, gives the most extensive available illustration of
the facts grouped under this law. In the first place, the farmer is
subject to it by mere location. The product of a field near his house and
barn costs less exertion than the product of a more distant field. In the
second place, he is likely to have chosen for his first efforts in crop
raising the land most readily yielding its fertility in crops. If he
extends his operations to less productive soil, he must work more for t