From Introduction: "The mining methods described and discussed in this report have been considered historically-that is, from early to present practice. The data for this report were collected during 1927."

From Introduction: "The effect of rock pressure may be general and continuous disintegration and reduction in size of pillars of ore and rock left for the support of the workings, resulting in the collapse of hanging wall and the closing of stopes, drifts, and shafts, or the action may be sudden and violent and aside from seriously affecting the workings may present a real hazard to the operation of mines. The object in the preparation of this report is to add to the accumulated information and from the facts presented to make suggestions for protective measures to be taken when possible."

Report issued by the Bureau of Mines over studies conducted on the ground movement and support failure of Michigan mines. Factors involved in surface subsidence in the mines are discussed. This report includes tables, maps, illustrations, and photographs.