Florence Bell's PhD Thesis

Florence Bell arrived in Astbury's lab in 1937 with impeccable credentials - Girton College, Cambridge, followed by the Cavendish Laboratories and then the Physics Department at Manchester. Her work in Leeds resulted in her being awarded a PhD in 1939. During the course of this work she took the first photographs of diffraction patterns from DNA fibres, an example of which is shown below:

Bell's first X-ray photograph of DNA

Until the work of Maurice Wilkins and Rosalind Franklin in Kings College, London in the early 1950s, these were the only published diffraction patterns of DNA available - and they yielded a key piece of information - that the spacing between successive nucleotides in the DNA strand was 3.4 Angstroms. This information was later used by the U.S. chemist Linus Pauling when he proposed (an incorrect!) three-stranded helix model for DNA, and also proved to be vital to Watson and Crick's later double helix model of DNA.

You can read some key parts of Bell's PhD Thesis using the Open Source Bookreader Program below.

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As Bell's samples were a mixture of two different structural forms of DNA however, they did not show the central black cross pattern that Watson had instantly recognised in Franklin's pictures as being characteristic of a helix.

In 1951, however, a fresh photograph of much higher quality was taken in Astbury's lab...

From University of Leeds main library

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