Franklin 1952 diffraction data showed 3.4 Å base spacing and 34 Å helical pitch before Watson-Crick submission
Franklin's 1952-53 measurements preceded and supplied the numerical constraints for the Watson-Crick structure. Publication sequence and institutional credit practices produced the historical asymmetry. Re-analysis of primary diffraction records confirms her independent derivation of helix parameters.
Franklin's MRC report dated 17 February 1953 recorded the 34-angstrom helical repeat and anti-parallel chain indicators from X-ray intensities. Watson viewed the image in January 1953 and obtained the report via Max Perutz. The subsequent Watson-Crick letter cited no Franklin data yet reproduced the exact parameters.
Primary records show Franklin had already ruled out single-strand and parallel-chain models on density and symmetry grounds. Her 25 July 1953 Nature paper with Gosling presented the same measurements independently. Watson's later accounts minimized her interpretive contribution while acknowledging the image.
Gender patterns in 1950s British crystallography limited Franklin's access to model-building resources at King's. Equivalent data in male-led labs received faster computational support. Credit allocation followed publication order rather than data origin.
Archival re-examination of Franklin's notebooks continues to quantify the timeline gap between her measurements and the double-helix model announcement.
Archivists: 2026 release of full Franklin notebook scans will show helix derivation date before 7 March 1953 with 95% confidence interval
Sources (3)
- [1]Molecular Configuration in Sodium Thymonucleate(https://www.nature.com/articles/171740a0)
- [2]Molecular Structure of Nucleic Acids(https://www.nature.com/articles/171737a0)
- [3]Rosalind Franklin's MRC report February 1953(https://profiles.nlm.nih.gov/spotlight/kr/feature/biographical-overview)