This cube has four additional cubes of equal dimensions. This is effected by first drawing the cube in the order and then finding the centre of the upright line 5, that being the nearest corner line of this first cube. The centre being found at 10, take the line 10 to the vanishing point for that side of the cube; this will give the centres of all the other upright lines of that side of all the added cubes. The line 11 is drawn from the top of the corner line 5, through the intersection of 8 and 10, until it meets the ground line 1, at its junction with which the upright line is raised for the far corner line 12 of the second cube. The three other cubes are described precisely in the same manner, being found by the diagonal lines traversing each pair of the cubes, through the intersection of the centre line 10, with each perpendicular line raised from the meeting of the previous diagonal line with the ground line 1. It will be perceived that a further distance of twelve feet is added to one side of the geometrical scale, and marked A. This is done merely to prove the correctness of the first diagonal line 11, passing through the centre line 10, to determine the perspective depth of the second cube. For if a line be taken from the end of the geometrical scale A to the point of measurement on the horizontal line, it will be found to meet the ground line 1 at exactly the same point; thus proving the truth of both modes of drawing. The former mode, however, is more convenient where a number of cubes are to be drawn; as the geometrical scale might extend far beyond the limits of the paper, and consequently give much more trouble.