who/what exactly is the aforementioned ruler of france?
It was the political and social system of the Kingdom of France from the Late Middle Ages
Ancien Régime
The Ancien Régime (; ; literally "old rule") was the political and social system of the Kingdom of France from the Late Middle Ages ("circa" 15th century) until the French Revolution of 1789, which led to the abolition (1792) of hereditary monarchy and of the feudal system of the French nobility. 
who ruled france when the metric system was established Ancien Régime how is this system associated with clocks? Christiaan Huygens's pendulum marking the seconds gave rise to proposals to use its length as a standard unit
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Ancien Régime [SEP] Introduction
The Ancien Régime (; ; literally "old rule") was the political and social system of the Kingdom of France from the Late Middle Ages ("circa" 15th century) until the French Revolution of 1789, which led to the abolition (1792) of hereditary monarchy and of the feudal system of the French nobility. The late Valois and Bourbon dynasties ruled during the Ancien Régime. The term is occasionally used to refer to the similar feudal systems of the time elsewhere in Europe - for example, in Switzerland. The administrative and social structures of the Ancien Régime resulted from years of state-building, legislative acts (like the Ordinance of Villers-Cotterêts), internal conflicts, and civil wars.