Table 1 Scientific practices and exemplar quotes on visualization from Watson’s autobiography (emphasis added)

Observation

“It was downright obvious to her [Ros] that the only way to establish the DNA structure was by pure crystallographic approaches.” (p.49)

Analyzing and interpreting data

“Maurice’s X-ray diffraction picture of DNA was to the point. It was flicked on the screen near the end of his talk. Maurice’s dry English form did not permit enthusiasm as he stated that the picture showed much more detail than previous pictures, and could in fact, be considered as arising from a crystalline substance. And when the structure of DNA was known, we might be in a better position to understand how genes work.” (p. 23)

Prediction as Visual

“Six weeks of listening to Francis had made me realize that the crux of matter was whether Rosy’s new X-ray pictures would lend any support for a helical DNA structure. The really relevant experimental details were those which might provide clues in constructing molecular models.” (p. 49)

“Francis would survey the progress of the past few hours, bringing our listener up-to-date on how we decided upon models in which the sugar-phosphate backbone was in the center of the molecule. Only in that way would it be possible to obtain a structure regular enough to give the crystalline diffraction patterns observed by Maurice and Rosy” (p.57)

Model as visual

“The a-helix had not been found by only staring at X-ray pictures; the essential trick, instead, was to ask which atoms like to sit next to each other. In place of pencil and paper, the main working tools were a set of molecular models superficially resembling the toys of pre-school children. We could thus see no reason why we should not solve DNA in the same way. All we had to do was to construct a set of molecular models and begin to play – with luck; the structure would be a helix. Any other type of configuration would be much more complicated.” (p. 35–36)

Other aspects of scientific practice

“Virtually all biochemist, including Herman, were unable to understand the arguments of the X-ray people” (p. 23)

As model building did not appeal to her [Rosalind], at no time did she mention Pauling’s triumph over the A-helix. The idea of using tinker-like models to solve biological structures was clearly a last resort.” (p.49)