The forging for the 155-millimeter howitzer's recuperator is a block of steel weighing nearly 2 tons--in exact figures, 3,875 pounds. This must be bored and machined out until it weighs, with the accessory parts of the complete recuperator placed on the scales with it, only 870 pounds. It is scarcely fair to a modern hydropneumatic recuperator to say that it must be finished with the precision of a watch. It must be finished with a mechanical nicety comparable only to the finish of such a delicate instrument as a navigator's sextant or the mechanism which adjusts the Lick telescope to the movement of the earth. No heavy articles ever before turned out in American workshops required in their finish the degree of microscopic perfection the recuperators called for. We adopted from the French, the greatest of all artillery builders, four recuperators--one for the 75-millimeter gun, one for the 155-millimeter gun, another for the 155-millimeter howitzer, and the fourth for the 240-millimeter howitzer. These mechanisms had never been built before outside of France. Indeed, one could find pessimists ready to say that none but French mechanics could build them at all and that our attempt to duplicate them could end only in failure. Yet American mechanical genius "licked" every one of these problems, as the men in the greasy overalls say, and did it in little more than a year of time after the plans came to the workshops. There was not one of these beautiful mechanisms, in France the product of patient handiwork on the part of metal craftsmen of deep and inherited skill, that eventually did not become in American workshops a practical proposition of quantity production. The problem of building French recuperators in the United States, in short, may be regarded as the crux of the whole American ordnance undertaking in the war against Germany, the index of its success. It presented the most formidable challenge of all to American industrial skill. There were men whose opinion had to be considered and who were convinced that it was impracticable to attempt to produce French recuperators here. Although the superiority of these recoil devices in their respective classes were universally conceded, Germany had never been able to make them, while England, with the cooperation of the French ordnance engineers freely offered, did not attempt them. The French built them one by one, as certain custom-built and highly expensive automobiles are produced. When American factories proposed to produce French recuperators not only but to manufacture them by making parts and assembling them according to the modern practice of quantity production, the ranks of the skeptics increased. Yet, as we have said, the thing was done. The first of these recuperators ever produced outside of the French industry were produced in America and manufactured by typically American quantity methods.