Title: A treatise of trigonometry, plane and spherical, theoretical and practical. In which the several cases of plane and spherical triangles are solved, instrumentally and arithmetically. As likewise a Treatise of Stereographic and Orthographic Projection of the Sphere. In which the Principles and Theorems on which they depend, are clearly Demonstrated, and the Practice naturally deduced from those Demonstrations. Illustrated in the Stereographic Projection of the several Cases in Right and Oblique Angled, Spherical, Triangles: So that the Requisites may be found without Calculation, by Scale and Compass. To which is added a correct table of logarithms, sines, tangents and secants. By Sam Heynes, late Reader of the Mathematics to His Majesty's Engineers.