NOTWITHSTANDING the _Art_ of PERSPECTIVE must be acknowledg’d so
highly and indispensably requisite in the Practice of _Painting_,
_Architecture_, and _Sculpture_; that in the First of these especially,
nothing commendable can be perform’d without its Assistance: Yet such
have been the Difficulties and Obscurities met with in the first
Attempts, and so great the Perplexity and Confusion of Lines in the
Practice thereof; that the best Instructions, hitherto made _English_,
have invited very few to such a Prosecution of this Study, as might
render their Performances of this kind, truly valuable.
’TIS something unaccountable, that, among so many learned Persons as have
handled this Subject, _Priests_, _Architects_, and _Painters_; very few,
if any of them, have given Directions proper for shunning that Disorder
and Confusion of Lines, which, in most Instances, must necessarily
attend the Execution of their Rules: In all or most of which, the whole
Space for the Performance is confin’d between the Lines of the Plan and
Horizon; which, where the Scale is small, and the Height of the Eye not
very much advanc’d, renders the Work exceedingly confus’d; and where
those Lines are coincident, (which frequently happens) the Method becomes
utterly impracticable.
THIS Author’s great Experience in the Practice of _Perspective_, having
furnish’d him with excellent RULES for Shortning the Work, and Obviating
the foremention’d Difficulties; he has here very generously imparted
them, and especially the latter, in the Tenth and Eleventh Figures.
And tho’ on Perusal of the first three or four Plates, this Method may
possibly seem the same that some others have before made use of; yet
whoever shall diligently observe and copy the Rules and Examples of the
succeeding Figures, must necessarily acknowledge the great Advantage this
has in a Perspective-Plan and Upright, clear and distinct; whence the
finish’d Piece is deduc’d, without the least Incumbrance of the Work.
The Explanations of the Rules here given, are short and instructive;
and the Architectonical Designs produc’d to exemplify them, Noble and
Magnificent.
THE Manner of Designing, where the Perspective is drawn on several
Ranges of Frames one behind the other, and such Scenes of Theaters whose
Grooves lie oblique to the middle Line, is also here laid down: And by
our Author’s Method, _Horizontal Perspective_, or that of Ceilings, is
render’d less difficult than the _Vertical_, or that against an upright
Wall. Upon the whole, nothing seems wanting that may make a Work of this
nature complete; unless what concerns Designs which are either Circular,
or abound with many Columns: For the Performance whereof, the Author, as
he promises in the Sixty-fifth Figure, has, in a SECOND Volume, given
a Rule more proper for the purpose; which also may possibly be made
_English_ in due time, if this Part meet with Encouragement.
WHAT the Author once intended should make a Part of that Second Volume,
he afterwards inserted in the Ninety-third and following Figures of
this Book: In the last of which, particular Notice should be taken of
his Conclusion; _That if_ Painters _would not run into inextricable
Errors, they ought as strictly to observe the Rules of_ Perspective, _in
designing the Figures of Men and Animals; as they do in painting Columns,
Cornices, or other Parts of Architecture_.
THAT none therefore be discourag’d in their first Attempts, through the
Brevity or Silence of our Author; (who, writing in a Country where the
Principles of this Art are more generally known than with Us, had no
need to insist so long on some things, as might be thought necessary to
_Beginners_) we shall endeavour to speak as plainly as we can to a point
or two, most liable to be misunderstood, or to prove a Stumbling-Block at
the Entrance; and then add a Word of Advice to such as shall attempt the
putting these Rules in Execution.
THE Author, in both his Explanations of the first Plate, has given some
Account of what he would have his Reader understand, by _Designing in
Perspective_; and a right Conception of this point being of great Use to
facilitate the Work, we thought it not improper, to describe something
more particularly, what is meant by the Art _Perspective_: but shall at
present speak only of That, which, whether Vertical or Horizontal, is
receiv’d on a Flat and Even Superficies; This being of much the more
general Use, and, when rightly understood, renders the Difficulties of
the Circular or Irregular Surfaces, easy and familiar.
PERSPECTIVE is the Art of Delineating, on a flat Superficies, as a
Wall, Ceiling, Canvas, Paper, or the like, the Appearances of Objects,
as seen from One determinate Point: For tho’ in Works of great Length,
Two, Three, or more Points of Sight are sometimes made use of; yet such
may more properly be said to be Several Views conjoin’d, than One Piece
of Perspective: Of which see the Author’s Opinion, at the End of this
Treatise.
IN Perspective, the Eye of the Beholder is esteem’d a Point, from whence
Rays are suppos’d to proceed to every Angle of the Object. The Wall or
Canvas to be painted (which we shall here call the _Section_) is imagin’d
to intervene at right Angles to the Axis of the said Rays, and, by
dissecting them, to receive the Appearance of the Object, in greater or
less Proportion, as the Section is more or less remote from the Point of
Sight. Our Author’s Rule is, That the Distance of the Eye ought to be
equal to the greatest Extent of the Object, whether in Length or Height:
As, to view a Building that is a hundred Foot long, and fifty high; he
would have the Distance a hundred Foot: To view a Tower sixty Foot wide,
and a hundred and fifty Foot high; the Distance should be a hundred and
fifty Foot. This Distance is not strictly to be understood of the Space
between the Eye and the Object, but of the Space between that and the
Section, the Plan of which our Author calls the Line of the Plan, or
Ground-line; for it’s often requisite, that the Section be plac’d at some
Distance before the Object, on account of Projectures of Cornices, and
other Parts of the Work that advance, as in the Eighth Figure.
THE Place of the Eye, with respect to its Height above the Ground,
ought to be such, as is most natural and agreeable to the Object. Thus
in _Architecture_, the Basements and inferior Parts of a Building are
improper to be set above the Eye, and their Cornices and Entablatures
have but an ill Effect when below it. _General_ Perspectives indeed
require the Sight to be taken at a Birds View; and on other Occasions
the Place of the Eye may be vary’d: but the best and most general Rule
is, not to exceed five or six Foot Height above the Ground. The Height
of the Eye above the Ground, thro’ which a Line is drawn, call’d the
_horizontal_ Line, is set on by the same Scale of Proportion, as the
Design bears to the real Work; and the Point of Sight so plac’d therein,
as may render the Object most agreeable. From the Point of Sight, either
on one or both sides in the horizontal Line, you are to set, by the same
Scale, the Distance you stand from the Section. And by means of these
Points of Sight and Distance, and the Measures of the Parts brought on
the Lines of the Plan and Elevation of the Section, by the same Scale;
all the Examples of this Volume are reduc’d into Perspective; as is
manifest on Inspection of the Figures.
WHAT we would add, by way of Advice, is,
I. THAT you very carefully observe, what the Author understands by
_Breadth_, _Length_, and _Height_, in his Explanation of the Fifth Plate,
before you proceed to practise on any Figure; otherwise you’ll certainly
misunderstand him; especially in the Third Figure.
II. THAT the Rules of the Tenth and Eleventh Figures be particularly
regarded, for avoiding Confusion in the Plans and Uprights.
III. THAT from the Disposition of the Perspective-Plans and Uprights,
with respect to the finish’d Pieces in the Twelfth and many following
Figures, you would observe, with what Dispatch the said Pieces may,
without the Help of Compasses, be delineated by your Drawing-Square;
_viz._ the Perpendiculars from the Perspective-Plan, and the level Lines
from the Perspective-Upright, or Section.
IV. THAT you would accustom yourself in Works that have many Lines, to
make the Perspective-Plans and Uprights for each Part distinct, so as to
prevent all Danger of Confusion. Thus you may have one Plan and Upright
for the Basement of a Building; and when that is drawn on your finish’d
Piece, remove them, and place those of the Body of the House; and when
that’s complete, do so by the _Attick_, &c. always observing so to place
the Plan below, and the Upright on one side of your neat Draught, that
your Drawing-Square may command each of them; which will mightily shorten
your Work.
V. THAT the Author’s Advice of taking the Figures in Course, be strictly
follow’d in the Practice; which will be a great means to render the Whole
easy and pleasant.
THIS is the Sum of what we thought most proper to advertise you; and
have only this farther to request, That if any Mistakes may have escap’d
the Press undiscover’d, as we well hope there are few or none, you will
favourably correct and pardon them.
MONITA ad TYRONES.
_Concinnitatem ac symmetriam opticæ delineationes ædificiorum habere
nequeunt, nisi utramque mutuentur ab Architectura. Proinde necesse
est, ut in istius graphide ac intelligentia te aliquandiu exerceas,
donec uniuscujusque elevationis vestigium formare didiceris, ex eoque
eruere sectionem totius longitudinis, ut in Opere toto videre est,
præsertim figuris sexagesimaoctava & septuagesima. Siquidem ex vestigio
& ex sectione derivatur in opticas imagines congrua rerum singularum
profunditas._
_Subjiciam his consilium summi momenti; videlicet, egregiè intelligas
oportet figuram secundam, priusquam progrediaris ad tertiam, idemque
de cæteris dictum velim; nam singulas eo disposuimus ordine, ut quæ
præcedit, necessaria sit ad percipiendas eas quæ sequuntur. Si aliqua
sint in explicatione, quæ initio non intelligas, ipsum schema sæpius
diligenter inspicies; ac vicissim si aliqua desint in schematibus, ex
declarationibus ea supplebis. Lapsus verò quos deprehenderis, facilè pro
tua benignitate, mihi, ut spero, condonabis._
ADVICE to BEGINNERS.
The Perspective of Structures here treated of, can have no Grace or
Proportion, without the Help of Architecture. ’Tis therefore absolutely
necessary, that you employ yourself for some time in Drawing, and the
Study of that Art; till you can readily describe the Plan of any Upright,
and from thence project the Section or Profile, as is shewn through the
whole Course of this Work; and more particularly, in the Sixty-eighth and
Seventieth Figures: Forasmuch as the proper Depth of each Part of the
Perspective, is determin’d by the Plan and Profile thereof.
I shall add this one thing more, which is indeed of the last Importance;
to wit, that you endeavour to understand the Second Figure throughly,
before you proceed to the Third; and so of the rest: they being dispos’d
in such Order, that the Knowledge of the preceding Figure is always
necessary to a right Understanding of that which follows. If you meet
with any thing which at first seems difficult in the Description, a
diligent Inspection of the Figure may relieve you: And on the other
hand, if you find not in the Figure every thing you desire, you may have
Recourse to the Explanation. What Errours you discover in the Work, I
hope you’ll generously overlook and pardon.