The traversing mechanism moves the whole carriage, including gun, along the axle, about the spade as the center of rotation. The traversing screw moves the carriage by being rotated through nut set solidly in the axle. The axle and nut are stationary and the screw moves laterally by means of the traversing handwheel. Hence, the carriage being attached to the screw, must move when the screw moves. Inasmuch as the axle is straight, it must accommodate itself to the arc of the circle described about the spade as the center. It does so by moving tangent to the arc, and consequently one end moves to the front and the other end moves to the rear, carrying the wheels with them. From this it will be seen that before attempting to traverse the piece, the brake must be “off.” The movement of the wheels may be easily seen, if a pencil line be drawn across the tire just above the brake shoe and then the piece traversed. The line will be seen either to raise or lower according to whether the piece be traversed to the right or left. In filling the “brake” or recoil cylinder, good results have been obtained by merely leveling the gun and filling the brake cylinder until full. Trying to pour out one hundred cubic centimeters of the liquid after the brake is full, as the French drill regulations lay down, is almost impossible; and no bad effects will be noticed provided the gun does not become excessively warm during the firing. If it should become warmed up sufficiently to affect the recoil, level the gun, unscrew filling plug to release the pressure, rescrew, and continue the fire. In using the manometer gauge, to measure the pressure and the height of the liquid in the recuperator, it will be found that the valve in gauge adapter will sometimes stick open to the extent of letting out all the air in the recuperator tanks. The only sure remedy for this is entirely to dismount the gun, remove the adapter, and replace its valve packing, which no doubt will be found to be worn and frayed, or else some foreign substance will be found to be lying between it and its seat. The gauges should be tested about once in three months by means of a standard steam gauge testing apparatus, making the appropriate transformations if the tester be graduated to pounds per square inch as most steam testers are. It will be found that the maximum steam pressures used are rather lower than these gauges read, hence only the lower readings may ordinarily be tested. To set the pointer to the correct pressure reading, pull the pointer loose and apply a known pressure to the gauge. Set the pointer at the corresponding reading on the manometer and press it on tightly. In general, this is sufficient for practical work. After each firing the breechblock should be entirely dismounted and each part washed in caustic soda solution and then stippled with oil before reassembling.