Spherical trigonometry: for the use of colleges and schools / By the late I. Todhunter. Revised by J. G. Leathem. Todhunter, I. (Isaac), 1820-1884. Leathem, J. G. (John Gaston), 1871- ed. Spherical trigonometry. QA535 .T6 1901 514.6 TOS Includes index. London : Macmillan and co. , c1949. c1949. 1901 Text xii, 275 p. : eng