The chance observer might assume that once the Ordnance Department had succeeded in putting in production the cannon of various sizes described in the preceding chapter the battle of providing artillery was as good as won. But such was not the case. Even after the ponderous tubes had come finished from the elaborate processes of the steel mills, the task of the ordnance officers had only just begun. Each one of these guns had to be rendered mobile in the field and it had to be equipped with a mechanism to take up the retrograde shock of firing (the "kick") and to prevent the weapon from leaping out of aim at each discharge. Mobility to a gun is given by the carriage on which it rides. The device which absorbs the recoil and restores the gun to position is called the recuperator (in the case of the hydropneumatic French design) or the recoil mechanism. Carriage and recuperator, or recoil mechanism, together are known as the mount. The forging, boring, reinforcing, machining, and finishing of the gun body is not half the battle of manufacturing a modern military weapon; it is scarcely one-third of it. No ordnance officer of 1917-18 will ever forget the heartbreaking experiences of manufacturing the mounts, a work which went along simultaneously with the production of the cannon themselves. The manufacture of carriages often presented engineering and production problems of the most baffling sort. As to the recuperators, a short analysis of the part they play in the operation of a gun will indicate something of the nature of the project of building them in quantities. The old schoolbook axiom that action and reaction are equal has a peculiar emphasis when applied to the firing of a modern piece of high-power artillery. The force exerted to throw a heavy projectile 7 miles or more from the muzzle of a gun is equally exerted toward the breach of the weapon in its recoil. Some of these forces handled safely and easily by mechanical means are almost beyond the mind's grasp. Not long ago a touring car, weighing 2 tons, traveled at the rate of 120 miles an hour along a Florida beach. Conceive of such a car going 337 miles an hour, which is much faster than any man ever traveled; then conceive of a mechanism which would stop this car, going nearly 6 miles a minute, stop it in 45 inches of space and half a second of time, without the slightest injury to the automobile. That is precisely the equivalent of the feat performed by the recuperator of a 240-millimeter howitzer after a shot. Conceive of a 150,000-pound locomotive traveling at 53.3 miles an hour. The action of the 240-millimeter recuperator after a shot is equivalent to stopping that locomotive in less than 4 feet in half a second without damage.