This fixture should be provided with a reference leveling surface, so that it can be kept level as the balance deflects. 这种装置应该有一个水平基准面,以便在天平变形时能够使之保持水平。
ROLL is the instantaneous value of the angle between the reference plane and the horizontal, measured in an athwartship vertical plane. 横摇以从左到右通过舰身的垂直面,量度参考面与水平面之间所形成的即时角度。