But, though the General Staff of the A. E. F. demanded mobility for the artillery, it also demanded increased weight and range. To meet this requirement there were devised various types of railway-artillery, ranging in size from 7 to 16 inch, thereby making available for use on the battle-front numerous guns from our seacoast fortifications which could not have been used otherwise. Early in the war the Army borrowed from the Navy a number of 7-inch naval rifles on pedestal mounts, for which the Ordnance Department provided specially designed gun-cars, thus affording a powerful and yet mobile form of defense for our coasts in the event of submarine attack. The next performance worthy of note was the mounting on railway-cars of ninety-six 8-inch guns taken from various seacoast fortifications. Both of the above types of gun, as well as the 12-inch mortars, were mounted on the so-called Barbette carriage, which permits of all-round fire at any desired elevation. The 10-inch seacoast rifle and all sizes above it were mounted on the Batignolles type of carriage, which depends primarily on the track arrangement for its direction of fire. Both the Barbette and Batignolles mounts had, after the initial setting, all the characteristics of fixed emplacements, but with the added advantage of being able to advance or retire with a minimum loss of time. A third type of railway-mount, which was used very successfully by the French and which was being adapted for certain of our 10, 12, and 14 inch guns when the war ended, was the Schneider, or sliding type of mount. Though this mount also depends upon the track arrangement for its direction of fire, it has none of the features of a fixed emplacement, the force of the recoil being taken up by permitting the entire mount to slide back on the track during the recoil of the gun. The “Chilean project,” as it was known, consisted in mounting six 12-inch guns, which had been manufactured in the United States for Chile and were on the point of delivery when they were commandeered by our government, on special sliding mounts designed by the Ordnance Department. Still another venture was the mounting for railway use of a number of 14-inch guns loaned by the Navy to the War Department. But the most ambitious project undertaken by Ordnance in connection with railway-artillery was the production of the huge 16-inch howitzer, to manufacture sixty-two of which an entirely new shop had to be erected by the Midvale Steel Company. This, the heaviest railway-mount of American design, weighs, with its gun, nearly a million pounds. The design and production of a device which would absorb its recoil of _seven million pounds_ was in itself no inconsiderable engineering problem. Each of these monster railway-cannon has its own train, consisting of standard and narrow-gauge ammunition-cars, as well as cars for tools, for spare parts, for repair work, and for the crews. Huge as they are, rivalling in