Autograph Letter Signed, to the Rev. G.H.Puckle, praising “the best elementary book” on Conics. 2 pp. 7 x 4 inches, fine. St. Peter’s College, Cambridge, 29 April 1868. Edward Routh (1831-1907), Cambridge mathematician. Routh collaborated with Henry Brougham on the Analytical View of Sir Isaac Newton’s Principia (1855). He published a textbook, Dynamics of a System of Rigid Bodies (1860, 6th ed. 1897) in which he did much to define and systematise the modern mathematical approach to mechanics. He contributed original research such as the Routh–Hurwitz theorem.