Abstract: A device for measuring angles between an oriented axis and a vector is provided in the form of a flat plate of transparent material having at least two straight parallel edges and an arrow situated on the plate and parallel with said the edges; the plate has a number of zones marked on the surface thereof and a closed curve centrally located and a longitudinal line provided parallel to the edges on either side of the central zone. Markings are provided in the zones to facilitate the measurement of the angles without requiring removal of the plate from the surface on which the angles are being measured.