"A good example...is the case of the alpha helix. Pauling had set up a group to do X-ray crystallography of the subunits of the proteins, and they got very precise data that enabled him to build up the whole molecule from the parameters of the subunits. As you know, he did this successfully in 1948 in London, but did nothing about it because his final picture of the alpha helix in 1948 did not agree with the X-ray diagram of the whole molecule....He then waited two years, until 1950, when the group at I.C.I. in London published the first X-ray pictures of synthetic polypeptides. These synthetic polypeptides did not have the anonymous reflection that Astbury's fixtures had had, and could be accommodated to the alpha helix; and he then published the paper. I think he was hoping to do the same thing with nucleic acids, because enough had been published on the subunits for him to do it, but he was misled by the erroneous pictures of the whole molecule."

Robert Olby. Interview with Gerald James Holton. Plenary Sessions of the Conference on Transforming Conceptions of Modern Science, Bellagio, Italy. September 1969.

I discovered that Rosalind Franklin and Raymond Gosling were working together on the structure of DNA, but not in collaboration with Wilkins. Moreover, they had the best DNA preparation. This was a preparation of calf thymus NaDNA that had been given to Wilkins some two years earlier by Rudolf Signer, of Bern, and from gels of which material Wilkins was able to draw thin, uniform fibres showing sharp extinction between crossed polarizers. Gosling and Wilkins had obtained X-ray diffraction photographs from these fibres indicating a high degree of crystallinity, and were a great improvement on those obtained earlier by W. T. Astbury and Florence Bell in their pioneering studies of DNA. They achieved this by passing hydrogen through water and then into the X-ray camera so that the fibres were kept in a moist atmosphere during the exposure.

Hugh Wilson. H. R. Wilson, "The double helix and all that," Reflections on biochemistry, TIBS 13. July 1988.