Page:An introduction to linear drawing.djvu/85

66 end near I, and the point $$a$$ where it strikes the line P B will be the perspective point of the gable end. Draw the lines M $$a$$ and O $$a$$, and the gable end is completed.

Having found the point Q of the other gable end, by the rules given under fig. 9, draw the line K Q for the slanting side of the roof, and the line $$a$$ Q will form the ridge of the house.

Mark the actual height and length of the door or window upon the perpendicular line E M, and draw lines from these points to A. The perspective height of the door and window will be found between these lines. To find the relative distance of the door and window from the end of the building, mark off the real distance on the base line and draw a line from that point to the point of distance I or H, as the case may be, and the point where this line strikes the lower vanishing line of the door or window will be the perspective distance of the side of the door or window.

FIG. 11. PLATE II.

To draw fig. 11, first draw the front of the arcade D Q E G H and A R C. Find the common centre O on the centre of Q G, at the height of the base of the arch. From the centre O draw a line towards the point of view V until you strike the point N, the centre of the perspective arch L M, which will terminate the proposed arcade.

If the thickness X H of the first arch (if the arcade is composed of several arches) project, as often happens, then, on the perspective depths X and 3, raise the perpendiculars X Y and 3, 2, to the perspective line of the top of the walls. On the point U, the centre of the opening of the arcade, raise the perpendicular U E. To