contain a limited number of base units of physical quantities, the remaining units of the system being defined as derived from the base ones. In defining the derived unit of some physical quantity in absolute systems of units, one starts from the formula that expresses the relation between that quantity and other quantities whose units are base units or are expressed through the base units.
In the 1830s the German mathematician K. F. Gauss introduced an absolute system of units with the base units millimetre (the unit of length), milligram (the unit of mass) and second (the unit of time). For this reason the name “absolute systems of units” is often applied to systems built on three base units — those of length, mass and time — and sometimes in an even narrower sense, to the CGS systems of units, that is, to systems in which the centimetre, the gram and the second are adopted as the base units. The term “absolute systems of units” should be regarded as obsolete, since systems of units can also be built on a different basis.
In the 1830s the German mathematician K. F. Gauss introduced an absolute system of units with the base units millimetre (the unit of length), milligram (the unit of mass) and second (the unit of time). For this reason the name “absolute systems of units” is often applied to systems built on three base units — those of length, mass and time — and sometimes in an even narrower sense, to the CGS systems of units, that is, to systems in which the centimetre, the gram and the second are adopted as the base units. The term “absolute systems of units” should be regarded as obsolete, since systems of units can also be built on a different basis.