AbstractThroughout its history the principal function of cartography has been the supply of maps for navigational, engineering or cadastral purposes to a clientele interested tn the map primarily as a basis of mensuration. The interest of the map maker tended therefore to be restricted to projections whose properties facilitated accurate representation of direction, distance and area, to the neglect of other systems less well adapted to such purposes. The characteristics of the orthographic projection, formerly discounted, should now commend it for a greater role in cartographic communication especially in the space age. However, construction of the most frequently required oblique version by methods dependent on draughtsmanship, the camera or the computer may overtax either the patience or resources of the average cartographer. As an alternative, general mapping equations are derived and it is suggested that the pocket calculator can be used to evaluate these to provtde sufficient co-ordinates for plotti...