=The quadrant sight, model of 1918= (=Schneider=), is mounted on the left trunnion of the carriage, both in traveling and in action, and should not be removed by the battery mechanics. The principal features of the quadrant sight are: The cross-leveling mechanism, the elevating mechanism, and the angle of site mechanism. _The cross-leveling mechanism_ principally consists of the leveling worm, leveling stop, antibacklash spring, leveling clamp, and cross levels. By means of the cross-leveling mechanism the quadrant sight is adjusted to proper alignment with the bore of the howitzer. _The bracket_ fits into the trunnion on the left side of the carriage and is provided with four tennons which engage slots in the face of the trunnions keeping the sight in proper alignment with the bore of the howitzer. The bracket is screwed in place by the bracket bolt; the front end of the body of the quadrant sight fits into the cylindrical part of the bracket and is held in place longitudinally by four lugs. [Illustration: _QUADRANT SIGHT, MODEL OF 1918._ (_SCHNEIDER_)] The body of the sight is rotated by the _leveling worm_ engaging the worm segment cut on the under side of the body. The outer end of the worm is provided with a knurled hand wheel by means of which the leveling mechanism is operated. The leveling stop, secured to bracket, engages slot in the body, thus limiting the angular motion of the body in either direction. The rear end of the cylindrical part of the bracket is split and provided with a leveling clamp by means of which the body may be locked in position after it has been leveled. _The cross level_ is located on the rear edge of the sight shank and serves the gunner in determining the level position of the instrument. The level vial is a glass tube, closed at both ends, and partially filled with a liquid consisting of 4 per cent alcohol and 60 per cent ether, a small bubble remaining in the tube. Graduations are etched on the circumference of the tube to indicate the central position of the bubble. The vial is held in a level-vial tube, the ends being wrapped in paper and set in plaster of paris. The knurled cross-level cover fits over the holder and, together with the level-vial tube, are held in place by the cross-level caps, which close the ends of the holder. When closed, the cover serves as a protection for the vial. _The elevating mechanism_ consists principally of a sight shank, elevating worm wheel, antibacklash pinion, elevating worm, elevating worm eccentric, elevating scale drum, and scale drum housing. NOTES ON CARE OF THE 155 HOWITZER.