Introduction, 485. — Samuelson's postulate on social indifference curves, 486. — Importance to it of the concept of diminishing marginal rates of substitution, 486. — Assumption that it reflects the prevaijing egalitarian ethic and the concept of ' diminishing marginal utility, 487. — In fact it has little to do with “egalitarianism” and is much more closely related to “moderation,” 489. — Model showing Samuelson's postulate and some of the cases in which it may not hold, 489. — The problem of convexity and the relationship between “social” and “community” indifference curves, 495.

We present a framework for measuring the joint impact of labor unions on wages, employment, and days of work. Our particular application uses county level observations to measure the impact of unionism in West Virginia coal mining from 1897 to 1938. The widespread belief is that union-nonunion wage differentials in coal mining during this period were of the order of 50 percent or more. Our estimates are substantially less. We measure negligible differences in union-nonunion employment, while, in the 1920s, operating days in unionized mines were about 25 percent below those in nonunion mines.