_Another Example of a Geometrical Plan, with the Elevation of its
Length._
If you would delineate in Perspective the Pedestal P, which you here
see divided into four Parts, and shadow’d; you must make the two
foregoing Preparations; namely, the Geometrical and the Perspective.
By the _Geometrical_, I mean the Plan A, and the Elevation B; By the
_Perspective_, all that’s contain’d within G, C, D, E, O.
Then transfer the Geometrical Breadth CD of the Plan A, into CD of
the Ground-line; and the Length DE of the said Plan into DE of the
Ground-line working after the usual manner; and you will have the Plan in
Perspective. Again, set the Elevation HX on CG of the Perpendicular, and
drawing the Visual GO, elevate thereto every Angle made by the Plan on
the Line CO, and you have all the Heights necessary for the Profile.
Lastly, by the Compasses you transport on a clean Paper the Angles of the
Plan, which give the perpendicular Lines; and those of the Profile, which
give the level Lines. The Visuals you draw to the Point of Sight.