Rules · Proportion · Plans · Optics
Make the parterre oblong rather than square, since figures somewhat oblong look better on the ground than square ones; later practice made it as broad as the front of the house and about twice as long.
parterre oblong; later practice: width ≈ house front, length ≈ 2 × width
Dézallier’s own advice is loose: figures somewhat oblong, he says, look better on the ground than square ones, because a parterre is always seen in perspective from the windows or the terrace, and the far end is foreshortened. He lets the parterre be widened, lengthened or shortened to suit the site, as long as the change is modest. The firmer rule, a parterre as broad as the front of the house and about twice as long, so that the house seems to stand on it, is the later practice recorded in the encyclopedias, such as the Encyclopaedia Britannica of 1778.
Its patterns are graded in turn, the embroidery near the house and compartments or grass farther out, with narrow flower borders (plates-bandes) round them. These are rules of thumb, and Dézallier gives them as such: the eye and the site may require changes.
To find how thick the pier of an arch must be, divide the intrados into three equal parts; draw a line from the springing through the first division, and produce it beyond the springing by its own length. A vertical through the end of that line marks the outer face of the pier.
pier ≈ ¼ span (semicircle) · ≈ 0.23 span (equilateral) · less for a lancet
To unify a façade of two or more storeys, run a single order of pilasters or columns through all of them, from the base to the main cornice.
To combine the unity of a central plan with the direction a church needs, plan the space as an oval, set across the axis to widen the view of the altar, or along it to lead the eye towards it.
Divide the inside of a dome into coffers that shrink in step with the meridians as they rise, so that their perspective deepens the dome and draws the eye to the light of the lantern.
Let the wall of a façade curve in plan (concave, convex, concave) so that the front answers the street, the light and the space within, and the order bends with it.
Proportion every step so that twice its height plus its depth equals the length of a natural pace on the level: two feet, or 24 pouces.
2 r + g = 24 pouces ≈ 65 cm (modern practice: 60–66 cm)
Cite this page Chris Paton, “The parterre longer than it is wide”, The Textbook of Architecture, https://textbookofarchitecture.com/rule/dezallier-parterre-proportion. Text, drawings and models licensed under CC BY-NC 4.0.