In this valuable book Tubal Cain takes the reader beyond the superficial or the simply practical with explanations of the composition of steel its additives & the effects of different temperatures on its constituents. With a grasp of what changes are actually taking place in the metal the care needed in following the practical processes described becomes understandable & will lead to better & more consistent results. Flame salt bath & furnace heating are detailed with information on accurate measurement or recognition of temperature levels. For the average small workshop operative or model engineer the discourses on tool material hardening & tempering will be of most use & in this connection this book replaced the authors earlier Hardening & Tempering Engineers Tools providing a broader-based more detailed & up to date examination of the subject.