His next publication was in 1680 in the form of two "Epistolae responsoriae" ("Letters & Replies"), the one, "On Epidemics," addressed to Robert Brady, Regius Professor of Physic at Cambridge, and the other "On the Lues venerea," ("On Venereal Diseases") to Henry Paman, public orator at Cambridge and Gresham Professor of Physic in London.