¹ A short history of patent law and more detail on the patent data are given in Sullivan, Richard J., “Measurement of English Farming Technological Change,” Explorations in Economic History, 21 (07 1984), pp. 270–89.CrossRefGoogle Scholar

² Woodcroft, Bennet, Subject Matter Index of Patents of Inventions, 1617–1852 (London, 1857). Classification was based on the title of the patent.Google Scholar

³ Fussell, George E., Jethro Tull: His Influence on Mechanized Agriculture (Reading, Penn., 1973), p. 121.Google Scholar

⁴ The threshing machine illustrates the difficulty in attempting to date invention by decade. Andrew Meikle is credited with inventing the first effective threshing machine (Mingay, George E., “The Agricultural Revolution,” in Mingay, G. E., ed., The Agriculture Revolution: Changes in Agriculture, 1650–1880 [London, 1977], p. 40). Meikie received his patent in 1788.Google Scholar

⁵ Clapham, John H., An Economic History of Modern Britain (Cambridge, 1926), vol. 1, p. 458;Google ScholarErnle, LordR. E. P., English Farming Past and Present (London, 1912/1961), p. 367;Google ScholarChambers, J. D. and Mingay, G. E., The Agricultural Revolution, 1750–1880 (New York, 1966), p. 170.Google Scholar

⁶ For example, Mingay, “The Agricultural Revolution,” p. 37.Google Scholar

⁷ Collins, E. J. T., “Harvest Technology and Labour Supply in Britain, 1790–1780,” Economic History Review, 2nd ser., 22 (12 1969), pp. 456–58.CrossRefGoogle Scholar

⁸ Mingay, “The Agricultural Revolution,” p. 40 on the adoption of threshing.Google Scholar

⁹ Kerridge, Eric, The Farmers of Old England (Totowa, N.J., 1973), pp. 116–18.Google Scholar

¹⁰ Wilkes, Rogers, “The Diffusion of Drill Husbandry,” in Michinton, W., ed., Agricultural Improvement: Medieval and Modern (Exeter, 1981), p. 75.Google Scholar

¹¹ Chambers and Mingay, The Agricultural Revolution, pp. 70–71.Google Scholar

¹² Wilkes, “Diffusion,” p. 84, 70.Google Scholar Compare the history of coke smelting of iron in Hyde, Charles K., Technological Change and the British Iron industry (Princeton, 1977).Google Scholar

¹³ This approach is developed in detail in Simon, Julian and Sullivan, Richard J., “Population Size, Knowledge Stock, and Other Determinants of Agricultural Publication and Patenting: England, 1541–1850” (mimeo, Carnegie-Mellon University, 1985).Google Scholar See also Nordhaus, William D., Invention, Growth and Welfare(Cambridge, 1969), chap. 2.Google Scholar

¹⁴ This point was made by Rosenberg, Nathan. See his Perspectives on Technology (Cambridge, 1976), chap. 15.CrossRefGoogle Scholar

¹⁵ Chambers and Mingay, The Agricultural Revolution, p. 14.Google Scholar

¹⁶ McCloskey, Donald N., “The Industrial Revolution, 1780–1860: A Survey,” in Floud, R. C. and McCloskey, D. N., eds., The Economic History of Britain since 1700 (Cambridge, 1981), vol. 1, p. 108.Google Scholar

¹⁷ Chambers and Mingay, The Agricultural Revolution, pp. 69–70.Google Scholar

¹⁸ On population and invention see Kuznets, Simon, “Population Change and Aggregate Output,” in National Bureau of Economic Research, Demographic and Economic Change in Developed Countries (Princeton, 1960), pp. 328–30.Google Scholar See also Simon, Julian, The Economics of Population Growth (Princeton, 1977), pp. 73–81.Google Scholar

¹⁹ Deane, Phyllis and Cole, W. A., British Economic Growth, 1688–1959 (Cambridge, 1962), p. 143.Google Scholar

²⁰ Fussell, Jethro Tull, pp. 74–75.Google Scholar

²¹ Tull's own description was obscure (Collins, E. J. T., “Harvest Technology and Labour Supply in Britain, 1790–1780,” Economic History Review, 2nd ser., 22 (12 1969), p. 78).CrossRefGoogle Scholar Existence of the knowledge was necessary but not sufficient to bring forth the invention. On necessity and sufficiency, see Mowery, David C. and Rosenberg, Nathan, “The Influence of Market Demand Upon Innovation,” in Rosenberg, N., Inside the Black Box (Cambridge, 1982)Google Scholar, chap. 10. Wilkes (“Diffusion,” p. 94) thinks a lack of demand accounts for the lack of use of the drill until the 1840s.Google Scholar

²² This induced bias theory starts with Hicks, John R., The Theory of Wages (New York, 1932), pp. 124–25.Google Scholar

²³ Of 206 work days for farm laborers in the eighteenth century, 130 were spent threshing. Other farm activities and number of days: plowing and sowing, 12 days; harvesting grain, 28 days; making hay, 24 days; various other tasks, 12 days. From Slicher van Bath, B. H., “The Influence of Economic Conditions on the Development of Agricultural Machines and Tools in History,” in Meij, J. L., ed., Mechanization in Agriculture (Amsterdam, 1960), pp. 9–10.Google Scholar

²⁴ Ernle, English Farming, p. 360 on dressing cost; p. 488 on the price of wheat. I have not been able to reconcile Ernle's figures with the cost of threshing given here in Table 4.Google Scholar

²⁵ van Bath, Slicher, “The Influence of Economic Conditions,” pp. 9–10.Google Scholar

²⁶ Collins, E. J. T., “Harvest Technology and Labour Supply in Britain, 1790–1780,” Economic History Review, 2nd ser., 22 (12 1969)., p. 10.CrossRefGoogle Scholar

²⁷ Wilkes, “Diffusion,” p. 66.Google Scholar

²⁸ David, Paul, “The Landscape and the Machine,” in McCloskey, D. N., ed., Essays on a Mature Economy: Britain after 1840 (Princeton, 1971), pp. 145–91.Google Scholar

²⁹ Clapham, Economic History, p. 462.Google Scholar

³⁰ Healy, M. J. R. and Jones, Eric L., “Wheat Yields in England, 1815–59,” Journal of the Royal Statistical Society, 125, part 4 (1962), p. 572.Google Scholar

³¹ Based on Mokyr, Joel, “Demand vs. Supply in the Industrial Revolution,” this JOURNAL, 37 (12. 1977), p. 1008, equation (6). Nonlabor share of income and income elasticity of demand for agricultural goods are for 1801 and are his as well, p. 988.Google Scholar

³² Wrigley, E. A. and Schofield, Roger S., The Population History of England, 1841–1871 (Cambridge, 1981).Google Scholar

³³ Savings in seed based on Tull's experience given above. Yield: seed ratio taken from Slicher van Bath, B. H., “Agriculture in the Vital Revolution,” in Rich, E. E. and Wilson, C. H., The Cambridge Economic History of Europe (Cambridge, 1977), vol. 5, chap. 2, p. 81. If 90 percent of your output went to market using nondrill techniques and 96.66 percent of it went to market using the drill, the effective food supply rises by 6.66/90 x 100 = 7.4 percent. Wilkes disagrees with Slicher van Bath's view that overall yields do not drop, as Tull himself admitted his crops were not as large.Google Scholar See Wilkes, “Diffusion,” p. 67.Google Scholar

³⁴ Estimated for 1661–1850 using ordinary least squares. Period of observation is the decade. Estimated t-values in parentheses. Population figures from Wrigley and Schofield, Population History;Google Scholar food prices calculated from Phelps-Brown, E. H. and Hopkins, Sheila V., A Perspective of Wages and Prices (New York, 1981).Google Scholar

³⁵ These results must be taken with a large grain of salt. The estimated elasticity between population and patents seems very large; I believe it is because of an important omitted variable, available technology. See Simon and Sullivan, “Population Size.” The regression is useful for the purpose of the next paragraph.Google Scholar

³⁶ The estimated error term is smaller than the standard error of the estimate.Google Scholar

³⁷ Total number of patents issued in the 1830s was 2,712, and 4,664 in the 1840s. Calculated from Woodcroft, Bennet, Chronological Listing of Patents of Invention (London, 1857).Google Scholar

³⁸ I appreciate Peter Schran's suggestion on this.Google Scholar

³⁹ Ernle, English Farming, pp. 349–76.Google Scholar