[ LXXV]
Showing the Use of the Square and Diagonals in Drawing Doorways, Windows, and other Architectural Features
This example is from Serlio's Architecture (1663), showing what excellent proportion can be obtained by the square and diagonals. The width of the door is one-third of the base of square, the height two-thirds. As a further illustration we have drawn the same figure in perspective.
| Fig. 140. | Fig. 141. |
[ LXXVI]
How to Measure Depths by Diagonals
If we take any length on the base of a square, say from A to g, and from g raise a perpendicular till it cuts the diagonal AB in O, then from O draw horizontal Og·, we form a square AgOg·, and thus measure on one side of the square the distance or depth Ag·. So can we measure any other length, such as fg, in like manner.
| Fig. 142. | Fig. 143. |