Have a piece of glass as large as a half sheet of royal folio paper
and set thus firmly in front of your eyes that is, between your eye
and the thing you want to draw; then place yourself at a distance of
2/3 of a braccia from the glass fixing your head with a machine in
such a way that you cannot move it at all. Then shut or entirely
cover one eye and with a brush or red chalk draw upon the glass that
which you see beyond it; then trace it on paper from the glass,
afterwards transfer it onto good paper, and paint it if you like,
carefully attending to the arial perspective.