This figure differs from the others because they are solid cubes. Further, the geometrical scale is used for the two cubes, because, being only two, it will be found in this way that fewer lines will be necessary, leaving the figure less intricate and confused. The two frnt sides of the cubes are produced in the same way as far as line 10, which is the farthest corner line of the second cube. 11) The line is drawn from the extremity of 10 to the vanishing point of 7, the two lines being really parallel. 12) Is drawn from the top of 9 to the vanishing point of line 6, these also being parallel. 13) Is drawn from the top of the upright centre line 8, to the vanishing point of 11 and 7, these being all really parallel to each other. 14) Is the far ground line taken from the lower extremity of 9 to the vanishing point of 1, these lines being also parallel. 15 and 16) Are lines drawn from the corner end of 10 and 8 to the vanishing point of 4, the three lines being really parallel. 17 and 18) Are upright lines raised at the intersection of the lines 16 and 15, with the ground line 14, being the far corners of the cubes; they respectively will meet the intersections of lines 11 and 13 with 12. These lines will complete the figure.