DISSERTATION XXXIV.

THE SCIENCE OF OPTICS INDISPENSABLY NECESSARY TO BE KNOWN BY THE ARCHITECT, TO ENABLE HIM TO ASCERTAIN WHAT PORTION OF HIS DESIGN WILL APPEAR AND WHAT RECEDE, WHEN HIS EDIFICE IS ERECTED.

"The emotion of sublimity is doubtless first produced by means of the power of vision: whatever is lofty, vast, or profound, while it fills the eye, expands the imagination, and dilates the heart, becomes a sort of pleasure to the beholder."BURKE.

This branch of natural philosophy treats of the mechanical properties of light and the phenomena of vision. The former are not much to our purpose, and have been a subject of speculation from the first dawnings of philosophy. Several of the earliest philosophers thought that objects became visible by means of something proceeding from the eye, while others maintained that vision was occasioned by particles continually flying off from the surfaces of bodies which met with others proceeding from the eye. Pythagoras is said to have ascribed the effect solely to the particles proceeding from external objects, and entering the pupil of the eye. It was not till about a thousand years after the time of Pythagoras that J. Baptista Porta fully satisfied himself and others of vision being performed entirely by the intromission of light into the eye, a doctrine now fully established; but it has often been a subject of inquiry, why we see objects in their true position when the image on the retina is inverted, but no satisfactory solution of the difficulty has ever been given: and we should be as likely to receive an answer if we were to ask, why we did not perceive every object bent because the image of it is depicted upon a concave surface. It is certain, that unless distinct images are painted on the retina, objects cannot be clearly perceived. If from too little light, remoteness, or any other cause a picture is indistinctly painted on the retina, an obscure or indistinct idea of the object is conveyed to the mind. The picture on the retina is therefore so far the cause of vision, that our ideas of visible objects vary as it varies, and when it is formed nothing is seen. Yet we may fairly conclude that the mind does not look upon the image on the retina, for in case of the gutta serena, a disorder which affects only the optic nerves, the pictures on the retina are as perfectly formed as in the best eyes, although the patient is afflicted with incurable blindness. It is the optic nerve, therefore, which conveys the impressions made on the retina to the brain, but how they are there communicated to the mind is screened from the view of man. It has been supposed that we acquire by experience the habit of seeing objects erect; but there are many striking facts to prove the contrary persons who have been blind from infancy, and who have been suddenly restored to sight by a surgical operation, have not been led into the smallest mistake. In fact, no reason can be given why the mind should not perceive as accurately the position of bodies, when the rays reflected from the upper parts of those bodies fall upon the lower parts of the eye as if the contrary took place.

The advantages of having two eyes, even so far as we are acquainted with them, are not confined merely to improving the brightness of objects, and showing them in their true places. In each eye there is a spot where no vision takes place, and this spot, which is about the fortieth of an inch in diameter, lies exactly upon the insertion of the optic nerve, so that we cannot perceive the image of any object that fails upon it at the hinder part of the eye, provided the other eye be shut; but as the insensible parts of the two eyes are on the sides next each other, that part which is invisible to one eye is visible to the other, and therefore the whole is seen. To be satisfied of the existence

of such a spot, the following experiment may be resorted to. Let three pieces of paper be fastened upon the side of a room, about two feet asunder, and let the person place himself opposite to the middle paper, and beginning near to it, retire gradually backwards, all the while keeping one of his eyes shut, and the other turned obliquely towards that outside paper which is towards the covered eye, and he will find a situation (which is generally about five times the distance at which the papers are placed from one another) where the middle paper will entirely disappear, while the two outermost continue plainly visible, because the rays which come from the middle paper will fall upon that part of the retina where the optic nerve enters. Hence it is evident, that if the optic nerve had not been inserted on one side, the centre of our field of view would have been invisible.

The following is a summary of the laws of vision with regard to the figure of visible objects. First, if the centre of the eye be exactly in the direction of a right line, the line will appear only as a point. Second, if the eye be placed in the direction of a surface, it will appear only a line. Third, if a body be opposed directly towards the eye, so that only one plane of the surface can radiate on it, the body will appear as a surface. Fourth, a remote semicircular arch viewed by an eye in the same plane with it, will appear as a right line. Fifth, semicircular arches in a bridge viewed obliquely, will appear, through the conjunction with the introdoses, like Gothic arches. Sixth, a sphere viewed at a distance appears a circle. Seventh, angular figures at a distance appear round. Eighth, if the eye look obliquely on the centre of a regular plane or a circle, the true figure will not be seen, the former assuming a trapezium, the circle will appear an ellipsis.

When we look from one end towards the other of a long and straight row of houses on each side of a street, they appear gradually to diminish as they are further removed from the eye, though upon a nearer inspection they are all found to be of an equal size. Again, if we take a view of any single building of large dimensions, we perceive each side converging to a point, and assuming different forms from that of the original. Now it will be evident from the observations we have just made respecting the visual angle that this must be the case, for the angle under which similar objects are seen, and consequently the evidence which sight affords us of their magnitude, is in an inverse proportion to the distance of those objects. The apparent exceptions to this rule apply to objects where the evidence of sight is corrected by the judgment. When objects are near we do not judge of their magnitude according to their visual angle. Though Though a man six feet high is seen at the distance of six feet under the very same angle as a dwarf only two feet high at the distance of two feet, still the dwarf does not appear as large as the man, because we are instantly able to make the requisite allowance for the difference of distance.

But when the distance is considerable, and we have no opportunity of comparing one object with another, we soon perceive that the rule just laid down has its foundation in nature. When Denon first drew near the gigantic pyramids of Gizeh, he was not particularly struck with their magnitude, principally because there were no objects in the vicinity by which a comparison could be made; but this impression was speedily effaced when he had observed a hundred people, who had preceded him, assembled at the base of one of them. The deception instantly vanished, a comparison was formed, and the stupendous pile assumed all its appropriate majesty.

The eye can only see a very small part of an object distinctly at once, for the lateral parts of an

* In the appearance of domes after being executed, there will be a great difference from that of the elevation. The modern Italian domes, however, have greatly the advantage in altitude of the ancient Roman, from their being mounted on loftier substructures; (such as that of the circular cell or tambour;) though we must still remember, that when that altitude exceeds a certain proportional measure, the effect of expansion is in the same degree reduced. It is from the different relative proportions between height and width that the cupola of St. Peter's appears so much less, and that of St. Paul's so much more than the ordinary beholder imagines.-(Author.)

object are not represented distinctly in the eye, and therefore the eye is obliged to turn itself successively to the several parts of the object it wants to view, that they may fall on or near the axis of the eye, where alone distinct vision is performed.* All geometrical elevations are deceiving without a perspective drawing, for we never see them so represented in reality. In an elevation the eye is supposed to be everywhere on the drawing at the same instant of time, whereas buildings when erected are seen from certain points, but only at one fixed point at a time. In elevations we see the relative proportion of one part to another, but we do not so see the parts in perspective; for here the soffits of all cornices are exposed to the eye, by which the cornices become enlarged; whereas the columns actually become contracted, hence the impossibility of deciding on the appearance of an elevation when executed without either a perspective drawing or a model;t and even if some parts are made too large for the others, they will then reduce the extent of the edifice. Other parts again, of an elevation which make up the pictures, such as roofs, stacks of chimneys, turrets, domes, &c., may all recede from the eye when the edifice is erected or become distortions; hence the necessity of certain points of view being ascertained, and visual lines drawn from the design to the eye, thus forming so many sectional pictures, and clearly ascertaining the appearance the edifice will assume when executed.

DISSERTATION XXXV.

ON DESIGNING AND DRAWING THE ELEVATIONS FOR A COUNTRY HOUSE.

"Blend simplicity with ornament, extent with proportion, and combination with unity."-MICHAEL ANGELO. The architect having thoroughly understood the conveniences which are required in a house, and devised his ground-plan, now proceeds with the corresponding elevations: here he is to remember, that the exterior part of a building is intended to please and strike the eye of others as well as that of the owner, and that whatever may hereafter appear to be a fault to a judicious observer, will reflect on the architect. Let him further consider that it will be of no consequence that he is able to defend what he has done by precedent, for whatever appears amiss to others, he may not be at hand to give his reasons to those who make the objections. Besides, the business of the architect is not to be able to answer such objections, but to prevent them; for this reason let him set out upon right principles, and by reconsidering his elevations, strike out whatever does not please his eye and judgment: let him not spare the labour of alteration where it is important, for in so doing it is but pursuing a course of study, and aiming at further perfection. Alterations are easily made on paper, but afterwards with difficulty and expense; it is, therefore, only by considering the parts well together as a whole, that he can succeed in these particulars, or, where rules are wanting, distinguish what is best.

We have already laid it down as a rule, that the situation and scenery are to point out or dictate,

* An Englishman when he first views an Italian landscape, makes the most egregious mistakes in estimating the distances of places and objects by the eye. He has no conception of the clearness of the air in that delightful climate, by which he is enabled to perceive objects at the distance of twenty miles with so much distinctness, that he supposes himself to be within half an hour's walk of them. Italian painters, true to the characteristics of their country, have made their most distant mountains well defined at their summits, and all other objects proportionately distinct, and we are apt to think they have deviated from nature, because the scenery of our own country is never clothed with such fascinating splendour. —(A.)

+ How wise was the proceeding of the ancient architects in designing and making their mouldings of a size proportioned to the distance from which they were to be viewed! The smaller a building, the more delicate in proportion may be its members; whereas if a building be very lofty, besides the increased dimensions, many parts require to be retrenched altogether, so that what remains may be more distinct; for the eye hardly reaches in pure vision through a mass of air, charged, perhaps, with vapour to a great height, without such a device.-(B.)

and guide us in the choice of the style and composition of the masses; nevertheless so fixed are the notions of some of our architects in their admiration of classical architecture, that this style has too been often adopted where other styles would have been more appropriate, such contending that the Grecian and Roman architecture is not only the most sublime and grand, but that those styles have exhausted every form of grace. Now we are not going to contest the grandeur of the lofty, bold, and finely-proportioned columns of the Greeks and Romans, the majesty of their pediments, the sublimity of their peristyles, and the inimitable and living beauty of their statuary and storied friezes; and if we could but gaze on the fair structures of Athens and the gigantic piles of Tadmor, I have no doubt that we should feel and confess that nothing in that character, and for those climates, ever could or ever will surpass them while the world stands.* Here then let the architect remember, that whatever component parts are grand or beautiful in architecture, whatever is noble and characteristic, or whatever is most surprising or effective in situation, is to be, by the magic power of genius, brought into view; combining it in the best manner, and adapted to excite correspondent emotions. Probably consistent with that variety which characterizes genius, is another essential quality required in an edifice-unity of design. In every building the architect should have one leading design; every part should have some relation to the next, and all should unite to produce one regular whole,

Denique sit quidvis simplex duntaxat et unum.

Of beauty in buildings, the inferiority of the moderns, compared in this respect with the ancient masters, is great; surely the use of decoration without correctness and effect of outline is an evident blemish. Now that for which the ancient masters are so eminently superior to the modern architects, is that elegance of outline: almost every one of the old buildings, however exceptionable in part of detail, has a grand, a beautiful, and a picturesque outline. Numerous buildings, both in England and abroad, whether viewed in the distance or near, have an almost universally imposing and agreeable appearance: their considerable augustness shows that the architect designed the elegant outward shell of the building at once, so as to contain only all the internal requisites, without any unsightly additions, or from any necessity of enlargement of the pile afterwards; thus at first all became necessary to the picturesque massing and grouping together of those buildings which we now see, and was never lost sight of during the progress of the design.‡

When the front division is made, or formed into stories by string-courses, the young architect should

* The faults of classic architecture when applied to domestic are monotony of structure, heaviness of mass, and want of adaptability to the needs of varying climates. The former defects are felt where a number of buildings in the pure Grecian style are brought together; the latter cannot be remedied without gloom within, or violation of unity without. It is true, that the original defect of classic architecture has been so far overcome by the genius of Anthemius, the old Byzantine architect, Michael Angelo Buonarotti, the Italian, and since by the English Sir Christopher Wren, as to admit of those magnificent domes of Santa Sophia at Constantinople, St. Peter's at Rome, and St. Paul's in London; but this is a departure from the strict classic model, and an engrafting upon it of an Eastern idea.—(Howitt's Visit to Remarkable Places, p. 448.) + Genius, which is the power of invention, ransacks every region of nature, science, and art for materials upon which she may exercise her powers. The beauties of poetry cannot be completely relished without a habit of attending to those forms of nature from which the poet borrows his conceptions, and observing with accuracy the distinct features and peculiar characters of objects in the vegetable and animal world; nor can the excellences of a classic building be truly estimated but by those who have had a classic education.-(Dr. Aikin's Essay on the Application of Natural History to Poetry.)

What is the mode of practice now pursued by the untravelled architect, or such as have visited those noble monuments merely to copy their component parts, without studying the principles of the original? why, in most instances, very different. A copy of the exterior of some old debased building is adopted on a small scale and executed in bad materials; this pretended economical crust, in nine cases out of ten, is discovered eventually to be neither high enough, long enough, nor broad enough to contain properly all the accommodations and internal details of the building; hence are added the external incumbrances of lantern-lights, ugly domes, heavy and frightful chimneys, and other deforming excrescences, for which modern buildings are so noted.

If a building at a distance appear monstrous, it is in vain that it have delicate enrichments, and that it be composed of rich materials; it cannot please either the vulgar or the tasteful, nor can the scientific give it commendation. The qualities of form

then consider the apertures or openings in each division; here are to be windows as well as doors in the front, and as there are other apparent and external parts to be arranged and united, those now come under consideration, which must be carefully proportioned; first, to the general aspect of the building, next, to the stories, and, lastly, to one another. The proportions of windows, string-courses, and attic-cornices to the stories, will serve as a rule to judge whether each is properly constructed for the whole, and also whether those divisions have been well made. It is a test to which the young architect must bring his own design, and it will either confirm his approbation, or show him that he has satisfied himself too easily in that division.*

The young architect we now suppose has drawn out his design, so far as the external part of the edifice is concerned, and that he is enabled to proceed; but we must not quit this important article without giving him a needful lesson, namely, that he entertain a modest sense of his own abilities, (yet a sufficient and well-grounded confidence,) and also support his opinions if controverted in any part with the strongest reasons but in the gentlest words. The proprietor of the intended edifice will claim a right to please his own fancy in laying out his money, and it is right he should be indulged if he so chooses, even at the expense of propriety in some of the minor parts, though not without being informed of it by his architect. If he desires to have any alteration in the design, let the architect lay before him the reasons he has in view, and the impropriety and the consequence of what the proprietor wishes to introduce; probably he will be won over by this to what is right; if not, the architect has done his duty in respect to him, and to the intended building; but he is to go no further: let him at least drop it for the time, and leave all to the future consideration of his principal: the proprietor will, perhaps, consult some other person upon the point, then it will be time enough to name it again before carrying this particular point into execution; he will then receive his final answer. Let him not be determined upon it because he is in the right, for the candid judge, when he sees a building executed in good proportion, will not believe that he who was capable of going so far right could fall into a gross fault; and therefore, though the error be obvious, he will charge it where it ought to attach, upon the arbitrary will of the proprietor, and not upon any defect in the judgment of the person who designed the edifice.

Finally, from the previous mode of designing flow all the beauties of architecture; hence the modus may be shifted, extended, varied, or methodically arranged into any form of a house. The proportions may afterwards be embellished, and beautified with enrichments discreetly disposed, more or less, just as the taste and genius of the architect may direct, all arising from that one unerring rule, harmonious combination, and true proportion. Just as may be said of the symmetry of a fine human figure, where all the proportions of the members are found to be exact. For

"Tis not an eye or nose, we beauty call,
But the full force, and joint result of all."

and outline stand apart from all the petty quarrelling about orders and styles, by which unskilful professors have pestered and lowered a once noble art.-(A.)

The most picturesque edifices of all countries have a wonderful similarity in their outline. The most perfect architectural composition is that which forms one immense pyramid of decoration, consisting of many minor subservient pyramidical masses. The pyramid is nature's own form: her mountains, the grandest of earthly masses, diminish to heaven: constructional, science requires that a building to endure should end in a pointed summit: a mere heap of sand will by its own gravity assume a pyramidical form, and so endure for thousands of years, and long outlive a wall of granite reared perpendicularly. (B.)

The inner construction of a house, some will tell us, is to be considered equally at the same time with the outer appearance: that in some particulars they depend upon one another, and that in these instances the disposition of the floors gives them a sufficient guide externally, this is in part true; but that any parts which are seen within the intercolumniations has any relation to its construction, or can be admitted as an excuse, must not be allowed. The dispositions of the floors are not seen on the outside, nor are the common marks of them visible, except sometimes by string-courses; he therefore errs who supposes this may be allowed as an apology.-(Author.)