Now lay your ruler across the upper left slope of the roof but put your centimeter marks on the blue paper and not on the white roof.
Use your ruler as a straight edge and lay it across the left vanishing point and the first dot you drew on the white line. Make sure the ruler is touching both places before you draw the next line.
Draw a nice dark violet line from the white line to the back of the barn and stop. Don't try to estimate because you are learning to use this mathematical system to make the parts of the picture the correct size.
THE ART POEM
