Simple Theodolite, Italian, 17th Century

Circular plate with tangent rule. The plate has a scale of 360° surrounding a scale of the 8 winds, each divided to 45°. The rule has a divided bevelled edge and three scales: equal parts [0] to 90; equal parts [2] to 20; and a non-linear scale [0?] to 162. The alidade carries two hinged sights, with holes and fixing screws for threads. One end of the alidade can be folded closed. The compass attached to the alidade appears to carry only a meridian line (cover glass corroded/etched). On the reverse is a shadow square (each side divided to 30) and an alidade.