Albert A. Michelsons experimentum crucis 1881 in Potsdam, Germany

This paper reviews briefly the history of the Michelson experiment, invented and performed for the first time in the Astrophysical Observatory Potsdam in 1881. The paper draws attention to the International Michelson Colloquium, held from April 27 to April 30, 1981 in Potsdam (Germany). This paper is an attempt to reconsider a scientific event organized 40 years ago, as the follow-up to Einsteinss Centenary in 1979, for Michelsons experiment done 140 years ago.