J.—: The Law of Diminishing Return (p. 188)

Careful restatements in general accord with Mill's teaching are to be found in Marshall, Principles, i. bk. iv. ch. 3; and Nicholson, Principles, bk. i. ch. 10. For the results of the Rothamsted experiments, showing that “beyond a certain point the increase of crop is not in proportion to the increase in the amount of manure applied,” see Lawes, Is Higher Farming a Remedy for Lower Prices? Lecture (1879); and Hall, The Book of the Rothamsted Experiments (1905). The extent to which the formula of diminishing returns covers the facts of agricultural development is discussed by Schmoller, Grundriss, ii. § 233 (Principes, iv. pp. 427 seq.). But while Mill and the older theoretic writers distinguished between the law of diminishing return in agriculture and the fact (by some called the law) of increasing return in manufacture (cf. Marshall, Principles, bk. iv. ch. 13, § 2), and writers of the historical school tend to minimise the effect of the law of diminishing return even in agriculture, some more recent theoretic writers go in the other direction and declare that the law of diminishing return is universal and applies to production of all kinds. For the sense in which they use such language, see Clark, Distribution of Wealth, p. 208, and Seligman, Principles, § 88.