Fig. 225.
We proceed to make our ground-plan abcd high above the horizon instead of below it, drawing first the parallel square and then the oblique one. From all the principal points drop perpendiculars to the ground and thus find the points through which to draw the base of the pyramid. Find centres OO· and decide upon the height OP. Draw the sloping lines from P to the corners of the base, and the figure is complete.
[ CXXIV]
To Divide the Sides of the Pyramid Horizontally
Having raised the pyramid on a given oblique square, divide the vertical line OP into the required number of parts. From
A through C draw AG to horizon, which gives us G, the vanishing point of all the diagonals of squares parallel to and at the same angle as ABCD. From G draw lines through the divisions 2, 3, &c., on OP cutting the lines PA and PC, thus dividing them into the required parts. Through the points thus found draw from V all those sides of the squares that have V for their vanishing point, as ab, cd, &c. Then join bd, ac, and the rest, and thus make the horizontal divisions required.
| Fig. 226. | Fig. 227. |
The same method will apply to drawing steps, square blocks, &c., as shown in Fig. 227, which is at the same angle as the above.