This papaer describing the mining practice at the Central-Eureka mine is one of a series of similar papers being prepared by the United States Bureau of Mines on mining practices, methods, and costs in the various mining districts of the United States. The mining practices described in the paper are illustrative of the methdos employed in the exploitation of comparatively low-grade gold ores under the extremely heavy and swelling ground conditions which occur in the Mother Lode belt of California