It was only after her retirement that Cannell became a remarkable historian of mathematics. She charmed audiences on several continents, promoting interest in Green and early 19th-century mathematical physics, in the clear tones and pure vowels of prewar English, somewhere between Miss Marple and Dame Peggy Ashcroft.
Most mathematicians learn of Green's theorem and Green's functions, but widespread knowledge of Green himself dates only from the 1970s, when Cannell and other Nottingham colleagues worked to restore his windmill and his memory. It is now argued that the great 19th-century Cambridge school of applied mathematics, which included such luminaries as Lord Kelvin, James Clerk Maxwell and JJ Thomson, was fathered essentially by the self-educated Green in his 1828 Essay On The Application Of Mathematical Analysis To The Theories Of Electricity And Magnetism.
By the time of the bicentenary of Green's birth in 1993, the mill at Sneinton, now a Nottingham suburb, was working again, a stained-glass window to Green was unveiled in his Cambridge college, and a memorial plaque was placed in the floor of Westminster Abbey, a few feet from Isaac Newton's tomb.
In all of this, Cannell played a central role, not least through her biography, which outlines Green's influence on mathematical physicists -- from Kelvin in the 1840s, to Nobel laureate Julian Schwinger, the first to introduce Green's functions to quantum mechanics, Richard Feynman, and Freeman Dyson, who demonstrated the equivalence of the ap proaches used by Feynmann and Schwinger. Cannell's book placed Green studies, and the history of mathematical physics in the 19th century, in a new light. She located the scientist in his social and educational context.
Brought up and educated in Liverpool, of Manx stock, Mary Cannell won a scholarship to Merchant Taylors' school for girls, and read French, with subsidiary history, at Liverpool University. After a postgraduate diploma in education, she taught French in English schools, and English at a school in France. After the war, the experience of lecturing to the troops led her to spend the rest of her career in higher education, specifically in teacher training.
In 1960, she was appointed deputy principal of the new Nottingham college of education, where, as acting principal 14 years later, she supervised the amalgamation of the college with Trent Polytechnic, later to become Nottingham Trent University.
Her researches on Green were tireless, widespread and thorough. She talked to his descendants and even introduced two branches of the family who did not know of each other's existence. She made frequent visits to Cambridge, particularly to Gonville and Caius College, where Green became an undergraduate at the age of 40, and then a fellow, and to Queens' College to learn more about the Rev John Toplis, the Nottingham headmaster and Cambridge wran gler whom she identified as the person most likely to have guided Green, given his only 18 months of schooling.
Mary's prewar studies into French culture lent insight into the mathematical sources used by Green, and her interest in English social history enabled her to appreciate the unrewarding and frustrating position in which he lived -- that of a working miller and mathematical genius, struggling to find a voice in a period of social privilege and rigid class structure.
Mary Cannell was working on projects of one sort or another -- the Green website, the revised edition of the biography, research papers, the catalogue of papers in the University of Nottingham library -- right to the end, in days filled with her characteristic energy and enthusiasm.
She is survived by her nephews, David and Peter.
Doris Mary Cannell, educator and historian, born 19 July 1913; died 8 April 2000
20 June, 2000 © Guardian Newspapers Limited