Franklin continued to explore another major nucleic acid, RNA, a molecule equally central to life as DNA. She again used X-ray crystallography to study the structure of the tobacco mosaic virus (TMV), an RNA virus. Her meeting with Aaron Klug in early 1954 led to a longstanding and successful collaboration. Klug had just then earned his PhD from Trinity College, Cambridge, and joined Birkbeck in late 1953. In 1955 Franklin published her first major works on TMV in "Nature", in which she described that all TMV virus particles were of the same length. This was in direct contradiction to the ideas of the eminent virologist Norman Pirie, though her observation ultimately proved correct.