On what date did Franklin join Jacques Mering's Paris laboratory?

Rosalind Franklin joined Jacques Mering’s Paris laboratory on 14 February 1947. She became one of the researchers working at the Laboratoire Central des Services Chimiques de l’État, where Mering applied X-ray diffraction to materials that lacked the regular crystal structures traditionally studied.

Franklin’s move to Paris followed her wartime research on coal at the British Coal Utilisation Research Association. Her friend Adrienne Weill helped connect her with Marcel Mathieu of France’s CNRS network, which led to an interview and appointment with Mering. The Paris position was a major turning point in her scientific development.

Mering taught Franklin practical approaches to X-ray crystallography, especially for amorphous substances such as rayon and carbonaceous materials. She later used this expertise in studies of coal and graphite, coining the terms “graphitising” and “non-graphitising” carbon. The date is sometimes confused with the year she moved to Paris, but the question asks for the precise joining date.