George Eliot supported Ayrton's application to Girton College, Cambridge. There, Ayrton studied mathematics and was coached by physicist Richard Glazebrook. She also constructed a sphygmomanometer (blood pressure meter), led the choral society, founded the Girton fire brigade, and, together with Charlotte Scott, formed a mathematical club. In 1880, Ayrton passed the Mathematical Tripos, but Cambridge did not grant her an academic degree because at the time it did not award full degrees to women. Ayrton then passed an external examination at the University of London, which awarded her a Bachelor of Science degree in 1881.