Real Pied De Roy (or King) 18th Century Architectural Measuring Instrument From The Old Regime

18th century king's (or king's) foot in boxwood and brass. It is a folding rule used to measure and can be used as a false square to raise an angle. This pocket instrument, whose 2 sides are identical, measures 32.5 cm or one foot (measure of the old regime) and is divided by 12 inches (27 mm). I have seen and owned a number of instruments similar to this often, often all in wonderfully etched brass, however these measuring instruments also displayed the conversion of measurements from the old regime to the metric system. Here, this very well assembled object predates the metric system.