Drawing House Forms
A, B, and C show three types of triangular prisms: right, isosceles, and equilateral. When put together with rectangular prisms, they create the three basic house forms. D is a shed roof and E and F are gable roofs.
Ellsworth D. Foster ed. The American Educator (vol. 3) (Chicago, IL: Ralph Durham Company, 1921)
Courtesy the private collection of Roy Winkelman