I. Present disagreement on analysis of mine royalties, 290. — Ricardo's analysis, 291. — Modern writers: Taussig, Marshall, 292. — Limitation of Ricardian theory to settled countries and established industries, 293. — Rent of mineral land and agricultural land distinguished, 294. — Analysis of royalties in practice, 296. — II. Proof of the theory. Differences in royalties due to quality of coal, 297; to date of lease, location, fertility of mines, 299. — Relation of thickness to value of seam, 300. — The no-rent mine, 301. — Mine royalties in France, England, the United States, 302. — Graphic representation, 308. — Extensive and intensive margins; diminishing returns, 311. — III. Nationalization. Possible division of royalties if mines are purchased; if confiscated, 312. — Possible results under government operation, under lease to private operators, under free mining, 313. — Effect of nationalization on price of coal; on wages, 314. — Conclusion, 317.