Plōt'ting-seāle, n.
n. (Surv.) An instrument consisting of two ivory scales, one of which is at right angles to, and sliding upon, the other;—used in plotting, especially in plotting offsets from main lines.
n. (Surv.) An instrument consisting of two ivory scales, one of which is at right angles to, and sliding upon, the other;—used in plotting, especially in plotting offsets from main lines.