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.

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."

Technical paper issued by the Bureau of Mines over change and wash houses in the Lake Superior area. As stated in the introduction, "this paper, with a few exceptions, presents data acquired in a survey, made by the author, of change houses in the Lake Superior region. All buildings, equipment, and practices were studied with regard for the health and welfare of the miner" (p. 1). This paper includes tables, photographs, and illustrations.

Technical paper issued by the Bureau of Mines over studies in mine safety and communication. The methods and equipment used in the studies are presented and discussed. This paper includes tables, illustrations, and photographs.

Technical paper issued by the Bureau of Mines over the development of gas masks designed for fighting fires. The characteristics of the different types of masks in development are presented. This paper includes tables, illustrations, and photographs.