Errors in Pointing

—When the platform or ground upon which the gun stands is not level there is an error in pointing (except when compensating sights such as the pendulum hau e are used), which varies in direction with the circumstances of the pointing and in amount with the elevation of the piece. If the natural line of sight is pointed upon the object and the elevation then given by a gunner’s quadrant or other device, the shot will go to the side of the lower wheel. If the gun be depre ed, it will go to the side of the upper wheel. If the tangent scale or old pattern breech-sight is used with the ordinary fixed muzzle-sight, and it be placed on a chalk-mark just determined, the shot will fall on the side of the upper wheel. If the scale is placed on the permanent mark, the contrary will hold. If a socket or fixed breech-sight is used, the shot will fall on the lower or upper side according as the gun is elevated or depre ed.