Device graph which makes it possible to provide the distance to travel, at the time of preparation, the journey of a vehicue, of a hiking of horses or pedestrian, with a card routiere, marine or topographical

摘要

The plastic transparent overlay sheet contains a printed motif of crossing lines which form a multitude of equilateral triangles. The triangles represent precise proportional lengths to a particular unit of distance measurement. Groups of 5 triangles are delineated by thick lines. Method of determining distance involves placing the sheet on the map; tracing the route to be followed onto the sheet; removing the sheet from the map; counting the number of triangular segments crossed by the route and the distance is determined since each side of a triangle represents a real unit of measurement.