A lengthy Autograph Letter Signed, addressed ‘My dear Sir’, telling a story about an unexpected visitor at dinner, discussing arrangements to meet, visits, and much else. 4 pp. 7 x 4½ inches, fine. Wednesday evening, undated. Thomas Stephens Davies (1794?–1851), mathematician. Davies’s principal area of research was geometry.Among the numerous subjects which engaged his attention were the properties of the trapezium, Pascal’s hexagramme mystique, Brianchon’s theorem, symmetrical properties of plane triangles, the geometry of three dimensions, and stereographic projection. In 1834 Davies was appointed one of the mathematical masters in the Royal Military Academy at Woolwich. While there, he helped to publish several useful textbooks for the use of its students.