FOURTH FIGURE.
A double Square in Perspective.
The double Square A is made after the same manner as the former, by transporting, either with the Compasses, or folded Paper, the Breadth of every Line, as you see the Points 1, 2, 3, 4, 5, 6, on the Ground-line mark’d with the same Numbers; and from these draw Visuals to the Point of Sight. Then transfer the Points of Length 7, 8, 9, 10, into the Ground-line, as you see also in the same Numbers; and direct their Lines to the Point of Distance E. Where these intersect the Visual 6, 7, O, make Parallels to the Ground-line, and the Square is complete. The same is done in describing the middle Square, and that on the other Side.
FIGURA QUINTA.
Quadratorum vestigia cum elevationibus.
Figuram hanc in duas partes divisi; in superiori parte vides tria quadrata optica aliquantulum adumbrata, eaque tam inter se distantia, quanta est distributio super lineam plani. BC erit quadratum primum. Secundum erit in EF. Si ergo posueris longitudinem quadrati in BC, eamque duxeris ad distantiam, secabit in DD visualem AO. Si pariter posueris alterum spatium longitudinis ejusdem quadrati in EF, & duxeris ad lineam distantiæ, habebis secundum quadratum opticé. Idem facies de tertio, & de aliis, quæ distribuenda sunt.
In secunda parte. Si desideres supra totidem vestigia formare elevationes cuborum, & stylobatarum, ut in inferiori figuræ parte vides, satis erit ex omni vestigiorum angulo elevare lineas occultas, & apparentes, determinando altitudinem faciei L primo cubo, & anguli ejusdem faciei dabunt altitudinem omnium aliorum.
Immò etiam totidem cubos formare potes sine lineis occultis, ducendo solùm apparentes, ut vides in tribus expositis adumbratis, & nitidis, quorum perpendiculares sumuntur ab angulis vestigiorum, ut in superiori figura habes in H, & lineæ plani translatæ sunt ab angulis elevationis, ut videtur in F.
FIFTH FIGURE.
Several Plans of Squares, with their Elevations.