Salmon, William: Polygraphice; Or, The Art of Drawing, Engraving, Etching, Limning, Painting, Washing, Varnishing, Colouring and Dying: In Three Books ... (London, 1672)

Of Drawing. 73
XII. The VISUAL RAIES,
are those lines which proceed srom the
Visual point, through the Glass, to any
point higher or lower than the plain of
the Horizon.
XIII. DIAGONALS or lines
ofdiftanee are siich as are drawn srom
the point of diftance5to any other point,
higher or lower than the Horizon.
XIV. The OBJECT is that form,
sigure, body or edifice intended to be
exprefled in Perfpe&ive proportions.
ri ).............. „.........
C H A P. XXVII.
The General VraBice os PerJpe&ive.
I. T Et every line which in the Object
L» or Geometrical figure, is ftraight,
perpendicular, or parallel to its base,
be lb also in its Scenographick deli«
neation.
II. Let the lines which in the object
return at right Angles srom the fore-
right-side, be drawn Scenographical-