Complex sentence: Alfred Schmitt (1907--1973) was a French astronomer, active at Algiers Observatory in the 1930s and 1940s and at the Royal Observatory in Uccle, Belgium in the 1950s.
Split into simpler sentences: Alfred Schmitt (1907--1973) was a French astronomer. Schmitt worked at Algiers Observatory in the 1930s and 1940s and at the Royal Observatory in Uccle, Belgium in the 1950s.