Rosalind Franklin · Photo 51
Can you photograph something invisible?
That time, that place
King's College London. Franklin's assignment was to photograph DNA by X-ray diffraction.
DNA fibers were difficult. They shift between two forms with humidity, and if the forms mix the pattern smears into nothing. Her technical achievement was controlling humidity precisely enough to obtain each form separately.
Why this question
Among those photographs is the one numbered 51, showing a sharp X-shaped pattern.
That cross is the signature of a helix. And from the spacing of the marks you can extract numbers: the length of one full turn, the distance between strands.
Franklin was cautious. She would not state a conclusion until the data supported it.
What was found
In the meantime, something happened.
Wilkins, in the same laboratory, showed the photograph to Watson in Cambridge without her consent. Watson later wrote that his mouth fell open when he saw it.
Nor was that all. Numbers from an unpublished report she had submitted to the funding body were also passed to Watson and Crick.
They put those numbers into their model. In the 1953 paper, Franklin's name did not even appear clearly in the acknowledgments.
The shape of DNA could not be known
A sharp X-shaped diffraction pattern obtained by controlling humidity
She died of ovarian cancer in 1958, at thirty-seven. The 1962 Nobel Prize went to the three surviving men