THE THEORY OF INTEREST

§9. Examples of Influence of Periodicity of Income

We have considered supposed examples of the effect onthe rate of preference exerted by those changes in theincome stream due to the growth or waning of naturalresources and to the temporary influence of misfortunesand inventions. There remain to be considered examplesof more regular changes in the income stream of arhythmic or seasonal character. Though most personsare not aware of the fact, it can scarcely be doubtedthat the annual succession of seasons produces an annualcycle in the income stream of the community. This isespecially true of agriculture. Grains, fruits, vegetables,cotton, wool, and almost all the organic products flowfrom the earth at an uneven rate, and require for theirproduction also an uneven expenditure of labor fromman during different seasons of the year. Statistics ofconsumption show that the income enjoyed conforms ingeneral to a seasonal rhythm. Food products are usuallymade available in the warm months when crops ripen;logs are hauled out of the woods in the winter, floated tomills in the spring, and made into lumber in the summer.

But the tendency to a seasonal rhythm is modified bythe existence of stocks of commodities to tide over theperiods of scarcity. The ice of winter is stored for summer,and the fruits of summer are canned and preserved forwinter. Only so far as such storage and preservation aredifficult and expensive, or impair the quality of the goodsthus held over, or are impracticable, because of the per-ishable nature of the goods, does there remain any sea-sonal change in enjoyed income. The rhythm is differentfor different industries and for different classes of thepopulation. The farmer is perhaps the most typical for

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