GUILLE,
when Einstein introduced the cosmological constant into his field equations and afterward Hubble showed him the universal redshifts, Einstein called it the greatest blunder of his life.
The units is inverse of area and it is needed to validate the steady state theory of the universe. At that time, nobody believes the universe can expand or contract. So it is used to formulate a static universe.
http://scienceworld.wolfram.com/phys...lConstant.html