In Hartwick [3], it was shown that implicit in Solow's [10] model of intergenerational equity and exhaustible resources was the savings-investment rule: society should invest in re-producible capital precisely the current returns from the use of flows ofexhaustible resources in order to maintain per capita consumption constant. Population was assumed to remain

[Given a known demand schedule for a mineral at each instant of time and many deposits with different known extraction costs per ton (different qualities) and different known sizes, how should exploitation be organized? How does an exogenous change in the size of deposit i or in the extraction costs per unit in deposit i affect the program of exploitation? These questions are investigated for the case of extraction costs constant per ton for deposit i. The comparative static analysis parallels that for a problem with many income classes in location theory.]

I. The resource allocation problem, 341. — II. Commodity flow equilibrium, 344. — III. Transportation sector and land constraints, 345. — IV. The dual problem and producer and consumer equilibrium, 346. — V. A numerical example, 347. — VI. Concluding remarks, 350. — Appendix, 351.