Drill and code book of United States Power Squadrons
A 1916 drill and code manual issued by the United States Power Squadrons in Boston for civilian motorboat owners practicing naval-style formation maneuvers and signaling. Diagrams reduce boats to numbered hatched ovals, with dotted outlines marking prior positions and dashed arcs tracing turns dash usable as abstract movement notation, numbered marker shapes, and hand-drawn arrow and path motifs.
