History of the Metric System

On the eve of the French Revolution, June 19, 1791, King Louis XVI of France gave his approval of the system. The next day, Louis tried to escape France but was arrested and jailed. A year later from his jail cell, Louis directed two engineers to make the measurements necessary to implement the metric system. Because of the French Revolution, it took six years to complete the required measurements. Finally, in June 1799 the Commission sur l unite de poids du Systeme Metrique decimal met and adopted the metric system. It was based on the gram as the unit of weight and the meter as the unit of length. All other measurements were to be derived from these units. The metric system was adopted For all people, for all time.  

From the nine base units, over 58 further units have been derived and are known as derived units. There are two types of derived units those that have special names (see Table 2.3) and those that have no special names (see Table 2.4). An example of a derived unit with a special name is force, which has the unit newton (the symbol N) and is calculated by the formula N = kg Vs2. An example of a derived unit that does not have a special name is volume, which has the unit of cubic meter (no special symbol) and is calculated by the formula volume = m3.  

Electrical potential, potential difference, electromotive force volt V W/A 

Concentration (of amount of substance) mole per cubic meter mol/m2 

Electric charge density coulomb per cubic meter C/m3 

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