Recording of Roof Subsidence

SUBSIDENCE caused by mining operations has been a matter of interest for the mining engineer for just 111 years, since the Belgian Committee for study of subsidence in the city of Liege submitted its first report in 1825. This interest is fairly expressed in the enormous amount of literature that has since appeared on this subject. A bibliography, probably far from being complete, which preceded this study as a pre-liminary survey, comprises more than 800 titles. In spite of this fact the problem remains today as acute as it has ever been. The questions of as good a recovery as possible of the national resources, the safety of the operations, and the protection of private and public property are the important angles from which to look at the problem.