tangent sailing

tangent-scale, s. Ordn.: A species of breech-sight for cannon. Its base has a curvature corresponding to the circumference of the breech of the gun, and its face is cut into steps corresponding to angles of elevation. The height for each step is found by multiplying the natural tangent of the elevation in degrees by the distance between the base-ring and muzzle sight. tangent-screw, s . An endle screw tangentially attached to the index arm of an instrument of precision, enabling a delicate motion to be given to the arm after it has been clamped to the limb, and permitting angular measurements to be made with greater exactne than could be done were the movement entirely effected by hand.