Contributor(s): Professor June Barrow-Green | In 1916 the physician Ronald Ross published the first of three papers on the mathematical study of epidemiology or, as he called it, ‘pathometry’. The second and third of these papers appeared the following year co-authored with the mathematician Hilda Hudson. At the time Hudson, who had ranked equivalent to the 7th wrangler in the 1903 Cambridge Mathematical Tripos, was well known for her work on Cremona Transformations. So how and why did Hudson, a geometer, end up collaborating with Ross, winner of the Nobel Prize for medicine in 1902 for his work on the transmission of malaria? And what role did she play? In her talk June Barrow-Green shall discuss the nature and extent of their collaboration, as well as the content and significance of their work.