Open, semi-circular protractor with extended bottom bar. Ring outer scale reads 0-180 degrees, by one degree, and 180 to 0 degrees, by ten degrees, on the inner scale. Bottom cross bar has notch at middle, upper edge, for center of angle measurement.
Materiaal
"Iacobus Lusuerg Mutinensis Faciebat prope Coll. Rom. A°. 1672."
