_Several Plans of Squares, with their Elevations._
I have divided this Figure into two Parts; In the uppermost you have
three Squares in Perspective a little shadow’d, distant one from another,
according to their Distribution on the Ground-line. BC is the first
Square; EF the second. If you then set the Length of a Square on BC, and
draw Lines to the Point of Distance, they will intersect the Visual AO
in DD. In like manner, if you set another Length of the said Square on
EF, and draw to the Point of Distance, you’ll have the second Square in
Perspective. The same you may do in the third, and as many as you have
occasion for.
In the second Part you see, that if upon the fore-mention’d Plans the
Elevations of Cubes or Pedestals were requir’d, it would suffice to
elevate the occult and visible Lines from every Angle of the Plan; and
determining the Height of the Face L of the first Cube, the Angles of
that Face drawn to the Point of Sight, give the Height of all the others.
You may form the same Cubes without occult Lines, drawing only those
that are apparent, as you see in the three Cubes that are finish’d and
shadow’d; the Perpendiculars of which are taken with the Compasses from
the Angles of the Plan, as is shewn in HI of the upper Figure; and the
level Lines are transferr’d from the Angles of the Elevation, as in FG of
the same Figure.