Sighting angles

Nine out of ten wrong buildings are wrong because an angle was guessed. The cure is sighting. Straighten your arm fully, lock the elbow, close one eye, and tilt the pencil until it lies along the edge you want: a roofline, the top of a wall, the line of a receding street. Hold that tilt, swing your arm down to the paper without rotating the wrist, and draw a line at the same angle. Then check it against the nearest true vertical or horizontal on the page.

The question to ask is never what angle is it; nobody can judge thirty-one degrees. The question is how far off level is it, or how far off plumb. Those two references never lie, and the eye is very good at judging deviation from them.

Sight every major angle in a building before you draw it: the eaves, the ridge, the base line, the top of each receding wall. Sight again after you have drawn it. The second sighting catches most errors while they are still one line.