A wind-rose of directions and obliquities for the water book
Cardinal directions with 'equal', 'declining' and 'raised' obliquities, drawn as sphere and cones
A key of directions built on the four principal winds, east, south, north and west, labelled with the points a, b, c, d, e and f. Leonardo tabulates each direction three ways: as an 'equality' (a c to the east, a e to the west, a b to the north, a d to the south), as a 'declining obliquity', and as a 'raised obliquity'. Drawn beside the lists are a sphere divided into quadrants and several cones with lettered axes that model these orientations in space. The framework serves the notebook's study of water jets springing into the air, which is set out on the facing folio.
On this page
Four directions in three obliquities (equal, declining, raised)
Each cardinal direction is given three forms: an equality (a c east, a e west, a b north, a d south), a declining obliquity toward the same points, and a raised obliquity toward the same points. The lettered lines fix these orientations for the diagrams.
Partial wind rose labelling east, south, north and west
A rose fixes the four principal directions with the letters a, b, c, d, e, f: east at c, south at d, north at f b, west at e. It provides the reference frame for the equalities and obliquities.
Sphere and cones modelling the directions in space
A sphere divided into quadrants by a lettered cross and several cones with lettered axes are drawn to represent the equalities and obliquities as solid figures. They translate the tabulated directions into three-dimensional constructions.