Simplify the following text for a Grade 8 native English-speaking person.
Original: He was the director of the Cavendish Laboratory , Cambridge , when the epochal discovery of the structure of DNA was made by James D. Watson and Francis Crick in February 1953 .
Simplified: He was the director of the Cavendish Laboratory , Cambridge , when the discovery of the structure of DNA was made by James D. Watson and Francis Crick in February 1953 .