Original sentence: The 65 cm refractor — the first big astronomical instrument manufactured by the famous enterprise of Carl Zeiss Jena — was mounted in 1915, whereas the completion of the 122 cm mirror telescope was delayed until 1924 as a result of the First World War
Edited sentence: The 65 cm refractor — the first big astronomical instrument manufactured by the famous enterprise of Carl Zeiss Jena — was mounted in 1915, whereas the completion of the 122 cm reflector telescope was delayed until 1924 as a result of the First World War