the lubricating-oil in the guns from freezing at high altitudes—all these are provided by Army Ordnance. Down upon our own back areas swoop raiding enemy aircraft, tiny specks against the blue, travelling at 140 miles an hour—the most difficult targets in the world. But complicated instruments, designed by Ordnance, are sighted upon them, determining their altitude, speed, and direction, and taking into account the windage and the trajectory of the shell, predicting the exact positions of the planes when our antiaircraft artillery opens upon them. The slim barrels of a battery of antiaircraft guns, mounted on motor-trucks for mobility, are raised to the indicated elevation, and a salvo of shell goes whining skyward, each projectile fitted with a special fuse so delicate in action that contact with the thin fabric of an airplane’s wing is sufficient to explode it, and yet so designed that it will not explode if, in loading, it should be accidentally dropped upon the ground. Ordnance again. Night falls. The guns are silent. From along the line of the captured positions rise fireworks like those which delight the summer multitudes at Coney Island. Star-shell, fired from Veriy pistols, make graceful fiery arcs against the purple-velvet sky, bursting, as they descend, into fountains of sparks which illumine the positions where the weary Germans are. A night-bombing plane, prowling above the enemy’s lines, unable to see its target in the darkness, releases a parachute-flare which slowly sinks earthward, illuminating the ground for a radius of a mile as brilliantly as though it were day. From the American positions colored signal stars—red, green, white, or “caterpillar” combinations—fall slowly across the sky, conveying all sorts of cryptic messages to regimental and brigade headquarters in the rear, to the aircraft circling above, or to the patrols scouting in No Man’s Land. All these pyrotechnics were designed and made by Ordnance.