It is obvious, as Mr. Brett goes on to point out, that "the vibrations from blows of sufficient power and elasticity (or sharpness) to cause metal at a moderate heat to flow completely into the impressions of the dies," _i.e._ the blocks in which are cut the impression of the required forging, "and to make clean work, are calculated to destroy any rigidly built machine." Hence the fact, which a cursory glance at the hammers cannot fail to establish, that nothing has been overlooked or omitted in regard to detail in design, "not any of the parts affected by the work are bolted together or in any wise rigidly fixed; the guides are held and the dies set in position by flexible means, _i.e._ the lower end of each guide fits into a recess into the base block, the top end passes up into a socket having sufficient clearance for wood packing, the wood is intended to absorb the vibrations which pass up the guide-rod." The plant at Crewe as originally installed in 1899, by the late Mr. F. W. Webb, of "compound" fame, consisted merely of one "battery" of hammers, comprising two 7-cwt. stamping hammers, and one 5-cwt. "dummying" or roughing-out hammer, and although the production of small stampings for signal apparatus etc., was all that was attempted in those early days, little by little the variety of work became extended, embracing, ere long, locomotive parts of small dimensions such as brake-rod ends, joints, levers, handles, etc., with the result that as time went on and as ever-increasing experience with confidence proportionate accrued to the staff employed, jobs of still greater variety were successfully tackled. [Illustration: THE 4-TON DROP HAMMER. [_To face p. 148._] There are at the present time no fewer than eight "batteries" of hammers "in action" at Crewe, the actual number of hammers being twenty-two, and some idea of the extent of the progress made may be gauged by the fact that the yearly tonnage output of stampings rose from 400 tons in 1902 to 1450 tons in 1917, a time when the plant was largely devoted to the manufacture of a regular "pot-pourri" of essential munitions of war. It was primarily due to the urgent demands of the Ministry of Munitions for a supply of trunnion brackets, which, cast in steel, were proving defective, and which had "been considered almost impossible to produce as stampings," that Mr. Cooke determined on the course of laying down an additional hammer, having a "tup" weighing no less than four solid tons.