Open semi-circular protractor with set square extension on right side. Set square marked with extension of protractor angle lines from semi-circle, 140-180 degrees, by 5 degrees. Simply-divided scale for equal parts, labelled "Scala," along base bar of protractor. On upper edge of base, a cusp indentation marks the center for angle measurements. End of set square extension is scalloped. Simple outline for decoration, both sides. Inner edges of protractor are sloped.
Inscription/Sig.
Along base bar: "Dominicus Lusuerg F . Romæ 1729";
