The hyperbolic paraboloid
The saddle surface made of straight lines, and Félix Candela’s shells built from it: the umbrella, the groined vault and the eight-lobed “flower” of Los Manantiales.
The rules it illustrates
The hyperbolic paraboloid is made of straight lines. A saddle surface in which two opposite corners are raised and two lowered is a hyperbolic paraboloid; it contains two families of straight lines, so it can be formed with straight boards and yet has double curvature.
Strength from form. A thin curved shell carries load by the membrane forces in its surface, not by bending; so shape it to its loads and supports, and it can span great distances with a thickness of a few centimetres.
Where it appears in the book
In the styles Parametricism.
In the chapters Frame and Skin.