I was fortunate that after Ted officially retired but still came to work each day , I was able to work with them. The team was a very early adopter of his technique. I can recall Judy more than once telling me how gracious Hugo was on the occasions they met. I had the good fortune to experience this myself. Ted died a few years ago. Tony died about a week ago.
Judy died this morning, after much more than a decade with severe pain and disability. He was an expert on so many different aspects of crystallography, but perhaps above all he was a leading authority on the math and statistics we use. In fact, it was Ted who proved the correctness of the Rietveld technique.
Crystallographers prior to Rietveld would chain a fit for integrated intensities of individual powder diffraction peaks together with a structural fit, by using those output intensities as input to single-crystal software. With that approach, they would see very different standard uncertainties then called e. This from their view indicated that something was wrong with Rietveld's technique. Ted demonstrated that chaining least-squares fits together serially is perfectly valid statistically, provided that the covariance matrix from the first fit is used as weighting in the second fit — something not possible in standard single-crystal software as weights are input as a vector.
When Ted wrote software that allowed this, he showed the s. QED, the Rietveld technique gives correct answers. Ted was very proud to have gotten his crystallographic education in the UK; not a common thing for a US undergrad to pursue in the s, at a time when the country was rebuilding from WWII. Ted would sometimes mention different happy experiences he had in those years, but the one story I remember best was when he told us how impressed he was at the time to be introduced to Rosalind Franklin — when she came to see the lab where he worked.
Back then crystallographers knew who she was and what she had done, even if the rest of the world was yet to learn it. Ted was the editor for the initial edition of Volume C of International Tables of Crystallography and its first revision.
