[ CXXV]
Of Roofs
The pyramidal roof (Fig. 228) is so simple that it explains itself. The chief thing to be noted is the way in which the diagonals are produced beyond the square of the walls, to give the width of the eaves, according to their position.
| Fig. 228. | Fig. 229. |
Another form of the pyramidal roof is here given (Fig. 229). First draw the cube edcba at the required height, and on the side facing us, adcb, draw triangle K, which represents the end of a gable roof. Then draw similar triangles on the other sides of the cube (see [Fig. 159], LXXXIV). Join the opposite triangles
at the apex, and thus form two gable roofs crossing each other at right angles. From o, centre of base of cube, raise vertical OP, and then from P draw sloping lines to each corner of base a, b, &c., and by means of central lines drawn from P to half base, find the points where the gable roofs intersect the central spire or pyramid. Any other proportions can be obtained by adding to or altering the cube.
Fig. 230.