The Manner of drawing this finish’d Cornice, from the preceding Plan and Elevation, is the same with that so often shewn you. Admitting therefore, that the Lines of the Plan and Horizon, and the Points of Sight and Distance, have the very same Position in this, that they had in the preceding Scheme; all the Angles necessary for delineating the entire Cornice, are readily found by the help of two pair of Compasses; taking their Distances one way from the Ground-line; and the other way from a Line perpendicular to the same: Then drawing the visual and perpendicular Lines, and keeping the Place and Contour of the several Mouldings, you complete your Design.
In the Pedament the visual Lines are wholly occult; and the Points H and L, where the Pedament begins to break back, being of like Height, are found in one and the same Visual: And the same may be said of all Points that are of equal Height from the Plan; for all the right Lines, which in the Thirty-third Figure are Parallels to the Ground-line, in the Thirty-fourth and Thirty-fifth Figures are Parts of the visual Lines.
Fig. xxxvi.
FIGURA Trigesimasexta.
Præparatio ad figuram trigesimamseptimam.
In vestigio geometrico C, & in ejus elevatione AB, præcipuas tantùm lineas adnotavi, ne figuram confunderem, & ut studiosorum industriæ aliquid relinquerem. Linea plani EG habet divisiones latitudinis P, & longitudinis Q, vestigii geometrici C. Ex punctis latitudinis ducentur more solito visuales ad O punctum oculi; ex punctis longitudinis fient occultæ ad punctum distantiæ, quod extra lineam AB protenditur modulis quatuordecim: & ubi occultæ ex divisionibus longitudinis secant visualem FO fiunt parallelæ ad lineam plani EF, adhibitis sectionibus talium parallelarum cum visualibus, ad complendam deformationem vestigii.
Eædem lineæ quæ in vestigio deformato sunt parallelæ ad EF, prolongantur usque ad visualem EO, & continuantur cum aliis parallelis ad perpendiculum DE. Fiunt quoque visuales ad punctum oculi ex divisionibus elevationis AB translatis in perpendiculum DE; adhibitis sectionibus talium parallelarum cum visualibus, ad complendam deformationem longitudinis elevationis.