For some years past the author has experienced a constantly-recurring need of a practical treatise on this important class of machine tools, as well as of the processes used in the working of sheet metal, and has found that English writers on mechanical subjects appear to have generally neglected this branch of engineering. It is true that in describing certain processes incidental references are made to some special form of press devised by them, yet there does not appear to be any treatise dealing with the subject in a systematic manner. American writers also have apparently neglected this subject, save as a subsidiary section of a work dealing with other branches of mechanical engineering, and then only in books which are published at a price which is generally prohibitive to the ordinary mechanic or student, whose means are limited.

A possible reason for this general neglect may be found in the multiplicity of articles that are now being manufactured from sheet metal, each of which possesses its 2wp own individual shape, often involving a large number of steps or operations before it is attained. Thus it has become to a very large extent a branch of engineering that does not lend itself to a systematic treatment like many others, except at the hands of a specialist. The author has devoted many years to this branch of engineering, in which, in addition to operating the presses when made, he has had frequent occasion to design both the press and the tools required by it for special purposes. In consequence of the lack of any textbook of reference, he has found himself constantly going over the same ground as other engineers had previously, entailing in consequence the loss of much time; hence he ventures to think that in collecting together the knowledge obtained in his own practice, supplemented by an account of the results that have been already achieved in the use of these important labour-saving machines in the reduction of the costs of manufacture, a useful work will be the result. A systematic treatment of the subject seems impossible, so no attempt will be made in this direction, but a description of one or two generally used presses will be dealt with at first, showing how the simpler results are obtained, afterwards passing on to the consideration of the more complex operations, in which more than one stage is required to complete the work. By thus gradually building up from the simple form to the more complex, it is hoped that the reader will be able to follow along easily the gradual development of a most interesting class of tools, which the author ventures to think will he appreciated more and more by engineers, who are being pressed hard to produce cheaply everything that they manufacture in order to hold their own in the commercial race.