Part 9
In the Execution of this Work, you are to begin with the Geometrical Plan; in which the two Ranges of Circles denote the Columns, the other Lines shew the Pedestals, with the Projectures and Breaks of the Bases and Cornices. The Line of the Plan is AB, that of the Horizon CD, the perpendicular Line is AD. The Point of Sight is O, that of Distance D; wherefore this Figure ought to be plac’d as much above the Eye, as the Height DO. I have set the Point of Sight something without the Cupola, that the Eye might be less weary’d in viewing the Work, and embrace more of the Architecture, than it could have done, had the Point of Sight been in the midst. The Points of the Line EF are transferr’d into AG, part of the Line AD. The Center of the Plan I is continu’d to H, and from all these Points visual Lines are drawn to O. Then placing the Heights of every part both of the Cupola and Lantern on the Line AB, from the Points of those Divisions draw Lines to the Point of Distance D; and where they cut the Visual AO, erect Perpendiculars intersecting the Line HO; which Points are the Centers of the several Circles. On the Visuals, between AG, must be describ’d the Out-lines of the Columns and Cornices, in like manner as when a Geometrical Upright is rais’d from a Plan. This done, you proceed to the Delineation of the Cupola itself in Perspective, by transferring into the Perpendicular EO the several Centers of HO, by Parallels to HI, as LN, _&c._ On the Center, with the Interval LM, describe the Circle NP, for the Nose of the Cornice; and with the Semidiameter ST describe the Circle QR, and so of the rest. The Numbers 1, 2, 3, 4, shew how the Breaks of the Cornice are determin’d by Lines from the Angles of the Geometrical Plan tending to the Point of Sight, till they intersect the Circle: The Returns of which Breaks are made by Lines tending to the Centers of their respective Circles; as is plain from N 3, and N 4. In this Plan I have omitted the Corbels, lest I should too much encumber the Work.
Hence appears the Necessity of making the Geometrical Plan of the whole Cupola, the Plan of a single Column not being sufficient; by reason each requires its particular Delineation. And when the Work itself is to be drawn for painting, you can’t well take it from a small Draught by way of Net-work or Squares, but the visual Lines should be drawn in their proper places, and the several Centers found; in which, by fixing Strings, you may readily describe the Circumferences of all the Circles.
Figura Nonagesimaprima.
Tholus figuræ nonagesimæ, cum luminibus & umbris.
_Tholus quem vides in hac paginâ, pollicetur sibi vitam diuturniorem illo, quem super telario plano insignis amplitudinis, depinxi anno 1685. in Templo S. Ignatii Collegii Romani. Proinde si casus aliquis illum absumat, non deerunt qui ex isto eundem in melius reficiant. Mirati fuerunt Architecti nonnulli, quòd columnas anteriores mutulis imposuerim, id enim in solidis ædificiis ipsi non facerent. Verùm eos metu omni liberavit amicissimus mihi Pictor, ac pro me spopondit, damnum omne se statim reparaturum, si fatiscentibus mutulis, columnas in præceps ruere contingat._
The Ninety-first Figure.
_The Cupola of the Ninetieth Figure, with its Lights and Shades._
The Cupola in this Plate will in all Likelihood be of longer Duration, than that which I painted on a very large Table, for the flat Ceiling of the Church of S. _Ignatius_ of the _Roman_ College, _anno_ 1685. For if that suffer by any Accident, with the help of this its place may be supply’d by a better. Some Architects dislik’d my setting the advanc’d Columns upon Corbels, as being a thing not practis’d in solid Structures; but a certain Painter, a Friend of mine, remov’d all their Scruples, by answering for me, That if at any time the Corbels should be so much surcharg’d with the Weight of the Columns, as to endanger their Fall, he was ready to repair the Damage at his own Cost.
Figura Nonages. secunda.
Tholus octangularis.
_Ex circulo fiet octagonum, accipiendo medietatem quadrantis circuli, ut habeantur singula latera octagoni. In eisdem lateribus distribuetur vestigium geometricum totius architecturæ, cum projecturis omnium membrorum, juxta modum quem servavimus in limbo circulari figuræ nonagesimæ. Utiliter etiam fieret elevatio geometrica totius Operis; quamvis ob spatii angustias ego eam omiserim. Deinde positâ una cuspide circini in centro circuli, extendetur alia cuspis ad altitudinem singularum projecturarum inter spatium ~A~ & ~B~, ut hic vides: atque ope parallelarum, omnia transferentur in lineam ~CD~, ut fiat optica deformatio, quam poscit sectio elevationis, cum aliis præparationibus, ut in figura præcedenti. Nam hic quoque ope circulorum invenire oportet puncta extrema in prominentiis membrorum singulorum architecturæ: ut conjungendo puncta per lineas rectas, quæ forment facies octagoni, compleatur totum Opus._
Ninety-second Figure.
_An Octangular Cupola._
From the Circle describe the Octagon, by taking half the Quadrant of the former for each Side of the latter. On these Sides the Geometrical Plan of the whole Architecture is to be dispos’d, with the Projectures of all the Members thereof, in the same manner as was done in the circular Border of the Ninetieth Figure. It will also be expedient, to make the Geometrical Elevation of the whole Work, tho’ thro’ Want of Room I have here omitted it. Then placing one Point of the Compasses in the Center of the Circle, extend the other to the Height of the several Projectures between A and B, as you see in the Figure; and by help of the Parallels transfer them all into the Line CD, for putting the Profile of the Upright into Perspective, and drawing the other Requisites, as in the foregoing Figure. For here also, by means of the Circles, are found the extreme Points of the Projectures of the several Members of the Architecture; and by conjoining these Points with strait Lines agreeable to the Shape of the Octagon, the whole Work is completed.
FIGURA Nonagesimatertia.
Vestigium templi Ludovisiani S. Ignatii almæ urbis.
_Constitueram huic Libro finem imponere figurâ nonagesimasecunda; nihilominus ut satisfaciam precibus amicorum, cupientium addiscere modum reticulationis opticæ, quæ adhibetur in superficiebus irregularibus, ejusque memini figurâ octogesima octava, publici juris facere decrevi ejus construendæ methodum. Ipsiusmet retis ope delineavi non solùm ædificium mox repræsentandum, sed etiam figuras omnes testudinis templi Ludovisiani, in qua pingenda nunc occupor. Eademque reticulatione, quæ erit ultima figura hujus Libri, dabimus Operi nostro suum complementum; quum nulla sit superficies, in qua suas delineationes juxta Perspectivæ regulas, earum rerum Studiosi absolvere nequeant._
_Exhibet hæc figura vestigium totius templi. Quamvis enim non indigeam nisi testudine inter januam maximam & tholum; proderit nihilominus Architecturæ Studiosis, universi Operis elegantiam ac symmetriam per otium contemplari._
The Ninety-third FIGURE.
_The Geometrical Plan of the Church of S. ~Ignatius~ at ~Rome~._
I had once determin’d to end this Book with the Ninety-second Figure; but at the Request of some Friends, who were desirous to learn the Making of Perspective Net-work for irregular Surfaces, as was hinted in the Eighty-eighth Figure; I resolv’d to publish the Manner of performing the same. By the Help of this Net-work, I delineated not only the Architecture now to be treated of; but also each Figure in the Vault of the Church of S. _Ignatius_, which I am at present employ’d in painting. The Method is laid down in the last Figure of this Book, and entirely completes the same; there being no Superficies, how irregular soever, but the Studious may thereon describe, by these Rules, whatever Perspective he has occasion for.
This Figure contains the Plan of the whole Church; for though my present Design requir’d no more than the Vault of the Nave, between the great Door and the Cupola; I thought it might be nevertheless acceptable to the Curious in Architecture, to have a View of the whole Design, so celebrated for the Elegancy and Proportion of its Parts.
Figura Nonages. quarta.
Orthographia templi Ludovisiani.
_Vt magis tibi gratificer, orthographiam seu elevationem templi Ludovisiani in longum dissecti delineavi, cum omnibus mensuris quæ vestigio sunt communes; addito tholo juxta ideam Autoris. Ejus autem nondum constructi loco, positum est in ~A~ & ~B~ telarium cum tholo depicto, de quo supra in figuris nonagesimâ & nonagesimaprimâ._
Ninety-fourth FIGURE.
_The Orthography, or Geometrical Elevation of the Inside of S. ~Ignatius~’s Church._
For your greater Satisfaction, I have here given the Geometrical Upright of the Church dissected lengthwise, with all its Measures agreeable to those of the Plan; as also the Cupola design’d by the Author: Which not being yet built, instead thereof is plac’d between A and B, the painted Cupola before describ’d in the Ninetieth and Ninety-first Figures.
Figura Nonages. quinta.
Aliæ præparationes ad figuras nonagesimamoctavam & nonagesimamnonam.
_Ex hac figura in quatuor partes divisa, disces ex uno intuitu methodum qua sum auspicatus opticam delineationem templi Ludovisiani. Prima pars exhibet latus dextrum testudinis inter januam templi ac tholum. Secunda pars continet vestigium ejusdem testudinis, arcubus ac lunulis distinctæ. Tertia pars continet latus dextrum testudinis usque ad summitatem fenestrarum, unde incipit Architectura quam pingimus in fornice. Quarta pars est vestigium geometricum fornicis, cum prominentia quam habent arcus in summitate jam dicta fenestrarum. Fingimus autem eandem esse soliditatem, tum ædificii depicti, tum navis templi; solæ enim columnæ, quæ respondent pilis templi, prominent extra ædificium._
The Ninety-fifth Figure.
_Other Preparations to the Ninety-eighth and Ninety-ninth Figures._
By this Figure divided into four Parts, you will at first Sight perceive the Method I observ’d in beginning the Perspective Design of this Church of S. _Ignatius_. The first Part shews the right-hand Side of the Vault between the Door and the Cupola. The second contains the Plan of the same Vault, with its Arches and Lunettes. The third Part represents the same right-hand Side, to the top of the Windows; where begins the Architecture painted in the Vault. The fourth Part contains the Geometrical Plan of that part of the Vault which is painted; with the Lunettes made by the Arches above the Heads of the aforesaid Windows. The Disposition of the painted Architecture above, is the same with that of the Nave of the Church; save that, answerable to the Pilasters below, I have suppos’d Columns projecting over the Work.
Figura Nonagesimasexta.
Aliæ præparationes ad figuras nonagesimamoctavam & nonagesimamnonam.
_Prima pars figuræ hujus trifariam divisæ, repræsentat elevationem geometricam lateris templi supra coronicem, & ædificii in testudine pingendi. Secunda pars complectitur arcum testudinis maximum, & elevationem geometricam faciei ejusdem ædificii. Tertia pars exhibet vestigium totius ædificii pingendi in testudine, cujus amplitudo eadem est cum amplitudine navis, ut antea dicebamus. Porrò vestigium geometricum non minus necessarium est ad pingendum ædificium, quàm ad ipsum ex materiâ solidâ extruendum, ut alibi monuimus._
The Ninety-sixth Figure.
_Other Preparations to the Ninety-eighth and Ninety-ninth Figures._
In this Figure, which consists of three parts, the first represents the Geometrical Elevation of the Right-side of the Nave above the Cornice, and of the Design painted in the Vault. The second contains the great Arch of the Vault, and the Geometrical Elevation of the Front of the said Design. The third part shews the Plan of the whole Work painted on the Vault, the Extent and Disposition of which is the same with that of the Nave, as beforemention’d. The Geometrical Plan, as I have formerly hinted, is no less necessary for the painting a Design in Perspective, than it is for raising a Structure with solid Materials.
Figura Nonages. septima.
Alia præparatio ad figuras nonagesimamoctavam & nonagesimamnonam.
_Ut optica projectio vestigii & elevationis quartæ partis totius Operis distinctior evaderet, mensuras partium singularum quadruplicavi, eandemque methodum in hac delineatione tenui, quæ figuris octogesimasextâ, octogesimaseptimâ, octogesimaoctavâ, & octogesimanonâ, explicata fuit. Punctum oculi positum est in medio navis Ecclesiæ; punctum distantiæ est in lineâ ex quâ incipit arcus testudinis._
Ninety-seventh Figure.
_Another Preparation to the Ninety-eighth and Ninety-ninth Figures._
That the Perspective of the fourth part of the Plan and Elevation of this Work might be more distinct, I have in this Figure made the Measures of each part four times as big as in the former; and have kept the same Method in this Delineation, as was deliver’d in the Eighty-sixth, Eighty-seventh, Eighty-eighth, and Eighty-ninth Figures foregoing. I have set the Point of Sight in the midst of the Nave of the Church; and the Point of Distance is in the Line from which the Arch of the Vault springs.
Figura Nonages. octava.
Quadrans Architecturæ horizontalis in fornice, cum luminibus & umbris.
_Habes in hac paginâ quadrantem totius Operis, modo consueto erutum ex præcedenti: nimirùm, cuspide circini ex angulis vestigii accipiuntur lineæ perpendiculares; ex angulis verò elevationis desumuntur lineæ parallelæ, ac lineæ visuales ad punctum oculi._
Ninety-eighth Figure.
_A fourth Part of the Architectonical Design, painted on the Vault of S. ~Ignatius~’s Church; with its Lights and Shadows._
In this Figure you have a Quarter of the whole Work, drawn from the foregoing Figure, after the usual Manner; namely, by taking with the Compasses the perpendicular Lines from the Angles of the Plan; and the parallel Lines from those of the Elevation, as also the visual Lines to the Point of Sight.
Figura Nonagesimanona.
Alter quadrans totius Operis.
_Ob diversitatem duorum quadrantum, tum in longitudine, tum in luminibus & umbris, seorsim apponendum utrumque censui; ut in eis delineandis omnem difficultatem tibi adimerem._
The Ninety-ninth Figure.
_Another Quarter of the whole Design._
By reason of the Difference of the two Quarters, as well in Length, as in their Lights and Shadows, I resolv’d to describe them separately, that you might find no Difficulty in designing the whole Work.
FIGURA Centesima.
Modus reticulationis faciendæ in testudinibus.
_Opera quæ fiunt in planis, contenta sunt duplici reticulatione, ut notum est. Nam una earum fit in exemplari, altera fit in superficie in quâ ipsum Opus pingendum est. At verò testudines exigunt tres reticulationes. Prima fit in exemplari, quod supponimus delineatum esse juxta regulas Perspectivæ horizontalis. Secunda reticulatio constat ex funiculis, & est pensilis; cujus formam geometricam habes in ~M~. Locum ubi figendi sunt clavi qui sustineant funiculos, exhibent rectæ ~AB~, ~EF~: optica verò deformatio retis est in ~N~. Punctum oculi est ~O~, distantiæ est ~LO~. Itaque si imagineris, tempore nocturno, lumen candelæ aut lucernæ existere in ~O~, atque à reti ex funiculis projici lineas umbrosas in testudinem, eædemque lineæ pennicillo colorentur, habebitur tertia reticulatio ad pingendam testudinem necessaria._
_Dixi ~si imagineris~, quia in testudinem obductam tabulato, ac remotam à reti, & multò magis à lumine, vel projici nequeunt umbræ, vel nequeunt esse vividæ ac distinctæ, ut oportet. Itaque ubi nimia fuerit distantia, figes in ~O~ extremitatem fili; eóque usque ad testudinem extenso, utéris veluti radio ac lumine candelæ, ad notandum umbræ locum. Proderit etiam, ut super tabulato motum fili obsecundes lumine alicujus candelæ, quod ipsi filo proximè admoveas. Atque his aliisque adminiculis, tuâque industriâ, colores induces super lineis umbrosis, ac tertiam reticulationem absolves. Posset etiam rete ex filis figi in parvâ distantiâ à coronice, puta in ~GH~, unde incipit basis ædificii: tunc autem umbræ in fornice sunt magis distinctæ ac visibiles._
_Diligentissimè curabis, ne mensuræ exemplaris discrepent ullatenus à mensuris testudinis: ut rete incidens in angulos, arcus, aut lunulas testudinis, exactè respondeat reti exemplaris. Demum si in vitia quæ emendari nequeant, incidere nolis; scito, regulas omnes Perspectivæ horizontalis, æquè in hominibus aut animalibus, ac in columnis aut coronicibus pingendis, omnino servari oportere._
The Hundredth Figure.
_The Method of drawing the Net or Lattice-Work on Vaults._
For Works on a flat Superficies, two Net-works are sufficient; as has been already intimated: One drawn on the Copy; the other on the Table to be painted. But for arch’d Surfaces, or Vaults, three are requir’d: One made on the Copy, which I suppose drawn according to Rules of horizontal Perspective. The second consists of a Frame of small Cords or Threads, to be hung up; the Geometrical Form of which is M. The Lines AB, EF, shew the Place where this Frame is to be fix’d, in the same manner as the Perspective N. The Point of Sight is O; of Distance, LO. Therefore, if you imagine a Lamp or Candle fix’d in the Night-time at the Point O; the Shadows of the Thread, thrown thereby on the Vault, being trac’d by a Pencil, make the third Net-work requir’d for painting the same.
I say, _if you imagine_ a Lamp thus fix’d; because either the Scaffold to the Vault, or the great Distance of the Vault from the Net-work, or the greater of both from the Light, may prevent the Shadows from being thrown at all, or at least, may render them so faint, as not to be distinct enough for the purpose. Therefore, where this happens, instead of the Light fix one End of a Thread in the Point O; and extending the other to the Vault, make use of it as a Ray from the Lamp or Candle, for describing the Place of the Shadows. It will be also of great use, to second the Motion of the Thread with the Light of a Candle you may have by you on the Scaffold, holding the same near the Thread itself. By this, and other such Helps, which your own Industry will suggest, you may lay these Shadows in Colours, and complete the third Net-work requir’d. The Frame of Threads may also be fix’d nearer the Vault at some Distance above the Cornice, as at GH, where the painted Architecture begins; for the Shadows thrown on the Arch will by that means become more visible and distinct.
You must be very careful, that the Measures of your Copy are exactly the same with those of the Vault, that the Net-work thrown into the Angles, Arches and Lunettes of the Vault, may perfectly correspond with that of your Copy. Lastly, if you would not run into inextricable Errors; assure yourself, that all these Rules of horizontal Perspective are as strictly to be observ’d in the Figures of Men or Animals, as in painting Columns, Cornices, or the like.
_Ut Perspectivæ Tyronibus consulerem, qui fortasse non adeo facilè percipient duodecim primas figurarum explicationes, totidem novas explicationes hic addo._
For the greater Help to Beginners, and those who are less conversant in the Art of Perspective, I here subjoin a farther Explanation of the first twelve Figures of this Book.
FIGURA PRIMA.
Explicatio linearum plani, & horizontis, punctorum oculi, & distantiæ; de hoc ultimo pressiús.
_Tres lineæ diversi inter se nominis, & muneris, item, & duo puncta præcipuè necessaria sunt, ut delineatio quælibet opticè reddi queat: prima vocatur linea plani, secunda horizontalis ubi est punctum oculi; de tertia loquar in elevationibus: alterum de duobus punctis assignatur oculo, & vulgò dicitur punctum oculi; alterum verò assignatur distantiæ, à qua nomen habet. Punctum oculi notissimum est, punctum verò distantiæ non ità; in hujus igitur explicatione morabor, & ut clariùs ostendam quid sit, & quomodo formandum sit, selegi descriptionem Ecclesiæ geometricè habitam, quam in tres partes divisi, in vestigium, sectionem, & interiorem faciem, in qua facie velit quis pingere, seu delineare aliquid opticè, ut elongetur ad mensuram aperturæ quadrati ~P~, ut habes in vestigio, & ad mensuram profunditatis ~Q~, quam habes in sectione._
_Super faciem ~CCCC~ quam puta esse delineamentum, habes rationem, qua debes disponere supradicta puncta, & lineas. ~HI~ erit linea plani: ~NON~ erit linea horizontalis, quæ fieri solet distans à linea plani altitudine hominis, ut vides in ~B~. Punctum oculi erit in ~O~; punctum distantiæ erit in ~N~, ex qua parte malueris. Hoc punctum ~N~ debet tantum abesse à puncto ~O~, quantum tuo arbitratu tu vis procul esse ut videas profunditatem illius quadrati ~PQ~, sicut vides in exemplo vestigii, & sectionis; ubi rem velut in suo statu naturali exhibeo; in iis enim tam abest ~N~ ab ~O~, quam abest homo ab ~A~ ad ~DE~, & homo ~B~ in sectione, ab ~FG~, ubi est murus in quo pingendum, vel delineandum est._
_Si ulteriùs curiosè descriptionem hanc consideres, videbis quam bene respondeat quadratum ~P~ in plano, & elevatio ~Q~, ut naturalis status rei in sectione Perspectivæ positæ in facie ~CCCC~, quæ est delineatio. Videbis enim visuales, quæ secant in plano spatium ~RS~, ita pariter secare spatium ~TV~ in elevatione: & segmentum visualium ~XZ~ in sectione respondere ~YK~ in elevatione, quod demonstratione non caret._
FIRST FIGURE.
_An Explanation of the Lines of the Plan and Horizon, and of the Points of Sight and Distance; but more especially of this last._
For beginning any Design in Perspective, there are principally requir’d three Lines, and two Points: One Line where the Feet stand, which is call’d the Line of the Plan, or Ground-line: The second where the Eye is plac’d, call’d the horizontal Line: I shall speak of the third in the Elevations. Of the Points, one is assign’d to the Eye, the other to the Distance. The first of these is generally known, the latter not so well understood, though of great Use for giving the Removal or Depth of every Object. I shall therefore insist a while on the Explanation of the Point of Distance; and that I may more clearly shew what it is, I have chosen the Geometrical Description of a Church, which is divided into three Parts; _viz._ the Plan, Profile, and inner Face; in the midst of which Face one would paint a Piece of Perspective, that should seem to recede as much as the Square P in the Plan, and the Depth Q in the Profile.
On the Face CCCC, which suppose that of the Design, you see the Manner of disposing the two Lines and the two Points. HI is the Ground-line. NON is the horizontal Line, which is usually made a Man’s Height above the Ground line, as in B. The Point of Sight is O, the Point of Distance N, on which side you will. This Point N must be as far from O, as the Distance you determine to place yourself at for viewing the Depth of the Square PQ; as is exemplify’d in the Plan and Profile, where you see the thing as in its natural Position: And in them N is distant from O, as far as the Man in A is remov’d from DE; or the Man B in the Profile from FG, which is the Wall to be drawn or painted on.
If you farther and more strictly examine this Description, you’ll discern how well the Square of the Plan P, and the Elevation Q, correspond as if naturally put into Perspective on the Face CCCC, which is the Draught. For you see the Visuals which cut the Space RN in the Plan, cut the same Space TV in the Upright; and the Segment of the Visuals XZ in the Profile, answer that of YK in the Elevation; which needs no Demonstration.
FIGURA SECUNDA.
Quadratum opticè delineatum.