April 1951 Linus Pauling, a structural chemist, published research on the structures in protein applying quantum mechanics to chemical bonding. Most significant among these was the proposition of the alpha helix, a basic structure present in many proteins. King’s scientists were interested but, like JD Bernal, puzzled by the fact the model had no way of calculating the x-ray diffraction and therefore no way of testing it. At the request of Maurice Wilkins, Alexander Stokes devised a way of calculating diffraction from helices. Stokes used Bessel functions.