Fig. 59.
ABCD is the given square; from A and B raise verticals AE, BF, equal to AB; join EF. Draw ES, FS, to point of sight; from C and D raise verticals CG, DH, till they meet vanishing lines ES, FS, in G and H, and the cube is complete.
[ XVIII]
The Transposed Distance
The transposed distance is a point D· on the vertical VD·, at exactly the same distance from the point of sight as is the point of distance on the horizontal line.
It will be seen by examining this figure that the diagonals of the squares in a vertical position are drawn to this vertical distance-point, thus saving the necessity of taking the measurements first on the base line, as at CB, which in the case of distant objects, such as the farthest window, would be very inconvenient. Note that the windows at K are twice as high as they are wide.
Of course these or any other objects could be made of any proportion.