For the benefit of those uninitiated in the fascinating art of drop-stamping or forging, it may not be considered superfluous if a brief explanation is given of the principles embodied in the system, and for this purpose one cannot do better than read and inwardly digest the opinion which has been advanced by Mr. Brett, founder of the Brett Patent Lifter Company of Coventry and inventor and patentee of the hammer in question.[8] "Having in mind," he says, "that the plastic or forgeable condition of wrought-iron or steel, when obtained, cannot be retained beyond limited periods, especially in the case of articles having thin or light parts, when its duration is very brief," it rests with the engineer "to provide for the forger a suitable form of power for actuating the dies or tools by means of which properly-formed forgings may be obtained." Further, "this power must be capable of instantaneous application," similar in all essentials to that produced by the smith "with hand hammer or sledge; that is to say, a perfectly elastic blow of sufficient force to produce an immediate and substantial effect upon the material." [8] [Extract from Paper read by Mr. Brett before the Engineering Conference of the Institution of Civil Engineers, June, 1899, and published in _Engineering_, June 30th, 1899.] The secret of providing this particular form of power lies obviously in the Brett drop-hammer, and in it alone, and the method evolved consists in the raising of the hammer-head or "tup" between a pair of parallel and vertical guides to a certain height by pressure of steam exerted within an overhead cylinder; no sooner is this pressure shut off than the "tup" automatically descends by force of gravity, delivering the hammer-blow simply with the weight of its falling mass, and rebounding, is lifted once again by re-admission of the steam into the cylinder, preparatory to the next descent and the delivery of a further succession of blows. It is largely thanks to a flexible cord and strap connection between the "tup" and the piston and piston-arm working in the overhead cylinder that the blow delivered is not only "smashing" in effect, but altogether resilient, in direct contrast to that of a steam-hammer, the blow of which is more in the nature of a dull thud or a rigid push.