Dies are now used so extensively and have made possible such wonderful results in the rapid production of sheet-metal parts, that die construction has become a subject of great importance to everyone interested in modern manufacturing methods. This treatise deals with the two essential elements in the production of dies; namely, the designing of various types, and the methods of constructing them. It also includes a great deal of information on the practical application of different classes of dies. In any kind of machine or tool manufacture there is always some variation in the methods employed in different machine Shops and tool-rooms for doing the same general class of work, and diemakers are not an exception to this universal rule. In fact, there is probably a greater difference in the methods of die makers than is found in any other single branch of tool or ma chine manufacture, because of the almost endless variety of dies which has often made it necessary for diemakers to devise their own methods of procedure. Therefore, this treatise contains information which, to some extent, represents the practice and experience of different diemakers, and while, in some cases, there may be other and, perhaps, better methods for accomplish ing the same results, an effort has been made to deal with funda mental principles and present information that is not only reliable, but of practical value to those engaged in this kind of work.