Mining historian Kerby Jackson introduces us to a classic lode mining work in this important re-issue of Bulletin 21, otherwise known as "Timbering and Support For Underground Workings For Small Mines". Unavailable since the 1960's, this publication was originally compiled by the Idaho Bureau of Mines and includes time tested methods for timbering small underground gold and silver mines. Topics covered include the selection of caps and posts, the treatment of mine timbers, how to install mine timbers, repairing damaged timbers, use of drift supports, headboards, squeeze sets, ore chute construction, mine cribbing, square set timbering methods, the use of steel and concrete sets and other topics that the small underground miner will find of benefit. This volume also includes twenty eight illustrations depicting the proper construction of mine timbering and support systems that greatly enhance the practical usability of the information contained in this small book. Note: This edition is a perfect facsimile of the original edition and is not set in a modern typeface. As such, some type characters and photographs might suffer from slight imperfections or minor shadows in the page background.