S -15 TE NK 1505 .D3 1872 برنامه ها - - - - - THE NCIPLES OP FORM IN ORNAMENTAL ART. BY CHARLES MARTEL, pseud. Thomas Ielf. AUTHOR OF "THE PRINCIPLES OF COLOURING IN PAINTING.” FOURTH EDITION. Ars probat artificem. 356 LONDON: VINSOR AND NEWTON, 38, RATHBONE PLACE, anufacturing Artists' Colourmen, by Special Appointment, to Her Majesty, and their Royal Highnesses the Prince and Princess of Wales. PREFACE. a scientific basis, and any attempt to elucidate them without it, can only lead the student to confusion and disappointment. So far as the very limited space at command has permitted, the following pages will be found to contain a summary of the most important canons of Ornamental · Art in connection with Form and its treatment, in · Architectonics, and in the Ceramic Art. These sub- jects are chosen for their primary importance in Ornamentation, and the community of principles exist- ing among the various arts permits their application to the Technic arts generally: to all works, requiring or admitting of embellishment. It has not been thought necessary to enter upon the question of Colour, as that subject has been fully discussed in a scientific manner, by M. E. Chevreul, to whose work the student is referred. A book on so vast and comprehensive a subject as Ornamentation, admits of an infinite amount of illus- tration. Ornamental Art is best illustrated, not by engravings, but in the original works upon which it has been applied. The student will find abundant illustrations of the most instructive character in the treasures of art contained in the British Museum, in the Ceramic collection at the Geological Museum in Jermyn Street, and at the South Kensington Museum, All that relates to Architectonics receives most valuable illustration from the materials of the Courts of the Crystal Palace at Sydenham, EXPLANATION OF FRONTISPIECE. GENERIC FORMS. A. Straight Line and Cube. Z. Curved Line and Sphere PRIMARY FORMS. Straight Lines. B. 1. Cylinder. B. 2. Conoid. B. 3. Clavoid. Curved Lines. C. 1. Spheroid. C. 2. Ovoid. C. 3. Ogivoid. MIXED FORMS. Participating of the Cylinder and the Sphere, the curves being directed inwards. D. 1. Canopian. E. 1. Phocian. D. 2. Napiform. E. 2. Lacrimiform. D. 3. Turbiniform. E. 3. Pyriform. EXPLANATION OF FRONTISPIECE. MIXED FORMS, Participating of the Cylinder and the Sphere, the curves being inclined outwards. F. 1. Corolla widening from the upper third. F. 2. Corolla widening from the lower third. F. 3. Corolla widening from the upper third and narrowing from the lower third. CRATEROIDS, Having a Breadth of two to five times their Height. G. 1. Segmentary Crateroid. G. 2. Crateroid of five heights. Canopian. G. 3. Crateroid of three to four heights. Campanuliform. DISCOIDS, Having a Breadth of at least five times the Height. H. 1. Segmentary Discoid. H. 2. Canopian Discoid. Torus of the Doric Capital. H. 3. Tectiform Discoid. Covers, Feet of Vases, &c. STEMS, Having a Height of more than three times the Diameter. J. 1. Stem widening from the upper third. J. 2. Stem widening from the lower third. J. 3. Stem with double curve. Campanuliform of double curvature. INTRODUCTION. A love of ornament seems inherent to man’s nature; the character of his ornamentation is mainly dependent on the amount of civilization and refinement he enjoys. In the savage state he tattoos his skin, deforms his features, paints his body, and decks it with flowers, fea- thers, shells, &c. He next extends this ornamentation to his weapons and utensils : his calabash and tomahawk are tattood like his body: the ornamentation of the New Zealander and the South-Sea islanders, with other savages displays great taste and skill. In the pastoral state, the shepherd, while tending his flocks and herds, seeks to beguile the weary hours by ornamenting the staff of his crook with carvings sym- metrically disposed, and pleasing to the sight, by which he expresses his instinctive feeling for ornamentation, subsequently extended to other things. Ornamentation is superadded to utility. The denizen of the valley kneads the clay, and models an utensil; he dries it in the sun, or bakes it in the fire, and fetches water in it from the distant spring. In the first essays of his intelligence and activity, the forms he produces will probably be imitated directly from the models supplied by nature, such as the shell or the gourd. 14 INTRODUCTION. But soon his artistic faculty is developed; he adopts certain proportions of height and breadth; he mingles the curved line with the straight in suitable propor- tions, adds handles, and lo! a Vase is produced. The utility of the utensil for its destined purpose remains, the alterations introduced have not impaired its unity, and a work of Art is the result. In genial climes, the dwelling man originally provided for himself was of minor importance; he constructed it simply and rudely of wood : but on the temples dedicated to his Gods, constructed of the more enduring stone, he lavished all his skill and taste. The roof that sheltered his family rested upon pillars formed of the trunks of trees: in the temple, these pillars become columns. Marble replaces wood : bronze in sheets is substituted for the bark or tiles which covered the rafters. On the stones of the temple, he carved in relief, processions, dances, victories, &c., the admira- tion of future ages. Then arose Sculpture, the new product of a new art. The house was a shelter, a simple fact-the temple, the work of a higher intelligence, is a work of Art. Architecture unites with Sculpture as theory with practice. To Architecture all the arts of imitation and ornamentation are allied. The Ceramic, or potter's art, (from the Greek Ceramos, clay), receives its name from a quarter of Athens where Corcebus invented and established the art of working in clay. A street in Athens was called Ceramos, from the name of Ceramus, son of Bacchus andAriadne. Besides Athens, the cities of Corinth, Ægina, and INTRODUCTION. 15 Samos, celebrated for their architecture, were equally renowned in the remotest times for ceramic productions. Before the time when Demosthenes ruled the Athe- nians by his divine eloquence, before Phidias created his immortal types of perfect beauty, or his rival Apelles had attained to the pinnacle of art environed by a glory more durable even than his works, there existed at Athens a feeling of devout admiration, and perhaps of gratitude, for the ancient art of the potter. The portion of Athens we have named was the first school of taste, the primitive sanctuary where abstract form unceasingly elaborated and studied under the eyes of an inquisitive and free people, was revealed to the first architects. It is the Ceramic art that inspired the authors of those antique structures, which, renewed at a later date with the marbles of Mount Pentelus, became temples worthy of the Gods to whom they were dedi- cated. The souvenirs of these primitive times are effaced : the Greeks, vanquished by the Romans, transmitted, of all their arcana, only the sight of their works. After so many ages have passed away, these precious remains appear to us like the tables of a mysterious law, which succeeding generations believe they understand because they measure the structures. We are told—such and such are the proportions of a Greek order, there is our guide, such is the law : but we are not told from whence the law-giver derived his measures : from whence came to him so pure, so perfect a taste, or from what source he derived the feeling and sentiment displayed in his works. INTRODUCTION. 17 It appertains to the artist to discover this germ, and fructify it by ingenious developments. But whatever be the invention, the purity of the contours or the rich- ness of the ornaments, it is to general laws that every work of this nature we would compose must be sub- mitted. So far froin considering utility as foreign to æsthetics, we must make it the basis, the exponent so to speak, of works of art. Thus, a vase, whether it be of gold, silver, marble, ivory, clay, or glass, must have the power of containing, otherwise it is only a deceitful appearance, a work without object. A vase, even if it is never utilized, must be capable of being useful. An edifice without an object, one into which we cannot enter, that is useful neither to the living nor to the dead, fails in the chief of architectural conditions. Equilibrium and stability are also laws of beauty and durability. Solidity is a principle of art; strength does not exclude elegance, it is not even incompatible with lightness, from which results a kind of beauty. The harmony of the different parts of a whole, and the suitableness of its proportions are sometimes the effect of a happy accident, but always a necessary result of certain laws, which it is the object of these pages to unfold, and then apply the principles of analogy to the works of those great architects who, without models, con- structed edifices which we can now only measure and copy. 20 PRINCIPLES OF ORNAMENTATION. imagination, taste and fancy open to man the most beautiful and most difficult career, that of creation. The most remarkable Inventional ornaments of antiquity are meanders, plaitings, astragals, flutings, waves, labyrinths, &c. We may also regard as ornaments, modillions, dentels, guttæ, triglyphs, and mutules, the fine effect of which has no connection with imitation, from which it is commonly supposed they are derived. The Greeks ornamented the antefixæ of their temples with a very capricious variety of palm-leaf which strictly belongs to inventional ornament. The Byzantine epoch is no less rich; the ornamenta- tion of the archevolts presents us with the undulating chevroned torus; with foliated and flowered columns, which are banded, contorted, and chiselled with a thousand fancies. Diamond points, chequers, nail- heads, bezants, nebulæ, serrations, stars, &c., replace, in this architecture, the Greek and Roman modillions and dentels. The strange enlacings of the churches of Norway, at Urnes, Find, Hitterdall, Borgund; the sculptures of the cloister of Arles, of the baptistry and the white marble pulpit at Pisa, although far apart, are none the less of the same nature. In other climes, in Mexico, in Yucatan, we find the ruins of mysterious cities of which no history exists. “In the midst of these ruins, monuments of an incalculable antiquity are covered with sculptured ornaments of most bizarre invention. The remains which bear the names of Uxmal and Labnah, are a mass of inventional ornaments. The beautiful ornamental mosaics of the churches of Sicily and Italy belong to the Byzantine era. 24 PRINCIPLES OF ORNAMENTATION. of Grinling Gibbons (a Dutchman), but he belongs to the past rather than to the present, which possesses a rival in Wallis of Louth. III. MIXED ORNAMENT. The ornament par excellence is the Inventional. Imi- tation of nature constitutes an ornament, the title of which sufficiently expresses its origin. By means of cer- tain fictions, lines and inventions, which fashion nature by combining imitation and invention, we produce mixed ornament, and no axion is more true than that of Theo- philus: “However well the lines of demarcation be traced, something capricious always escapes the category.” The echinus of the Corinthian cornice is a very simple type of the mixed ornament: a well imitated egg alternates with a dart and two purely inventional curves. The ornamentation of a frieze also, may, at the option of the sculptor, cease to be imitation of foliage without ceasing to be a beautiful ornament; human figures, animals, birds, may be added, and so compose what we call mixed ornament. In this manner, with the addition of some carving, arabesque ornaments may be mingled with natural leaves to form a mixed ornamentation. Byzantine capitals often exhibit the example of birds mixed with enlacements which form a mixed ornament. If, to gothic tracery we join angels, flights into Egypt, scenes from the crusades, processions, &c. a mixed orna- ment full of charms will result. The sculptures of many of our own and of continental cathedrals afford examples Finally, we may rank among mixed ornaments a part COMPOSITE ORNAMENT. -25 of the so-called Renaissance inventions, but which in their principal models are derived from the Baths of Titus and the arabesques of Raphael. In this elegant kind of open-work, human figures, birds, chimeras, &c., mixed with foliage, exhibit purely fantastic convolutions. In ornamentation fancy is liberty. Provided this liberty be maintained with good taste, and do not degenerate into absurdity, fancy is the first qualification of the ornamentist. If in a piece of architecture or in a ceramic work we superpose different classes of ornaments, the result is a composite ornamentation. IV. COMPOSITE ORNAMENT. One of the finest examples extant of this kind of orna- ment is the Maison Carré in the city of Nîmes, built in the time of the Romans, by Greek architects, who, niasters of eurythmy, were the depositaries of the purest tradi- tions of analogical proportion. The flutings and lions' heads, the annulets and aquatic leaves, the modillions ornamented with foliage and geometric dentels, the ovoli and principal ornaments of the frieze unite in the most eurythmic combinations to the splendour of a whole, which may be submitted as the most perfect model of composite ornament extant. The capitals of the columns at Nîmes were worthy of the homage of the Greeks of Phigalia and Corinth. The ornamentation of the Ceramic art is generally composite: some lines of inventional ornament are de- veloped on the edges, necks, collars, and shoulders of a LAW OF SUITABILITY. 31 Generally, the architrave formed by the inclined lines of the roof, is an admirable crowning to the portico; it derives a portion of its value from the expression which it gives to the edifice, in indicating not only the façades, but also the middle of these façades. If the architrave raises itself too much at its summit, approaching the equilateral triangle in shape, it loses its expression; an architrave is so much the more beautiful, as the lines of the side differ more palpably from those of the base, up to a determinate point, where the pyramidal effect ceases. The law of suitability alone can account for the beauty resulting from depressing the architrave. In cold climates the feeling of comfort leads man to prefer high pitched roofs, which quickly carry off the rain and snow; never- theless, this vivid feeling is combatted by the evident beauty resulting from lowering the architrave; so power- ful is the influence of suitability in producing beauty. To distinguish the anterior from the posterior façade, the Greeks placed acroteria on the former; such as statues, sphinxes, bucklers, &c. It is in virtue of the law of suitability, that in the ceramic art, a flattened spheroid is more agreeable than the sphere ; for the same reason, a regular ellipsoid or oval, will please less than an ovoid ; if this truth was not proved by a thousand examples in human works, it would be by the works of the Creator, by the contours of a handsome face. We exclude the geometrical cube from beautiful forms, because it has no expression. We consider the square an ungrateful form destitute of expression, which should be SPHEROIDS. 49 the subject of conoids, the clavoidal form is but little employed in architecture. The laws of stability ex- clude it in the exterior construction of edifices. The ensemble of the Corinthian capital may be con- sidered as a chiselled clavoid ; the mason delivered to the sculptor a regular clavoid; the sculptor brings out the capital, executes the details, but the principal salients border on the contour of the primary clavoid. The torus of the capitals of the portico of Thoricus, that of the temples of Sunium and of Eleusis, is a clavoidal disc. We may also rank among the number of clavoids the corbelling of some edifices of antiquity and of the Middle Ages. Those of Hadrian's Tomb or the Castle of St. Angelo at Rome, certain gates at Avignon, the Tower of Beaucaire, &c. It has been stated, that the key of the vault is the re- presentation, par excellence, of the clavoid. It often figures in relief on semi-circular arches. The Egyptians, Greeks, and Romans attached a just importance to the key of the vault, and to its ornamentation. This im- portance the Greeks called Hurmonia. The Romans placed on it, in their triumphal arches, a statuette of victory, or of a conqueror. IV. SPHEROIDS. The sphere and spheroid are primary forms. Like the cube and the square, the sphere belongs more to geometry than to the beautiful formıs of art. In the same manner that the straight line is the 50 PRIMARY FORMS. shortest road from one point to another, the sphere is the form which contains the greatest quantity of matter within the smallest possible extent of surface. This consideration has a certain importance in Ceramic art, from which utility is not excluded. The sphere is, in every respect, the emblem of the most complete curve. The execution of a sphere, in sculpture, is a work of extreme difficulty. All that can be said of the form of domes, arcades, spherical vaults, all that we can describe of the intelligence, taste, and feeling necessary to the outline of the regular hemispherical curve, so much employed in architecture, is contained in a single precept:-Take a compass. It is true that the section of the sphere, or rather, the roundness in a horizontal direction, is an elementary condition of all the ceramic forms made on the potter's wheel. Therefore, this condition comes not in question, as we have considered form only as profile and in eleva- tion. For here the wheel perforins the office of com- pass; instead of turning around the object to describe it, we turn the object itself under mechanical pressure, from whence results a circular form, foreign to taste or feeling, and of abnormal intelligence. The sphere may combine with other elements in a composite vase ; its developments can only take the name of proportions relatively to the various elements of the composition in which the sphere is employed. The flattened spheroid (Frontispiece), having an aspect which distinguishes its breadth from its height, is in some of the conditions which bring it within the category of intelligent forms. It is the same with the OGIVOID. ellipsoid, which is distinguished from the sphere by different relations of height and breadth. Yet these spheroids of limited fitness, present few resources in fine ceramic compositions. A circle inscribed in a square, modifies its sterility by the effect of contrast. From a similar feeling, architects surmount a ball upon an isolated column with an elongated cone. The acute form of the cone stimulates, and the straight lines which form it, correct the nullity of the geometric block. The straight lines and the right angles of a cross being combined with the sphere, produce an effect of contrast still more satisfactory, and compose, as to art, an emblem of universality of forms; an emblem that is placed in the hands of kings as a symbol of their power, and also of the universality of the Christian religion. V. OGIVOID. The ogivoid is to the sphere what the conoid is to the cylinder. It is a spheroid, smaller at its summit than at its base; it is the egg, with the small end uppermost. The ogivoid is as important in Christian architecture, as the conoid (column) is in Grecian architecture. An ogival (Gothic) window presents the profile of an ogivoid with cylindroidal base; in the same manner as the gates of Mycenæ, or the propylæ of Eleusis, re- present the lines of a conoid. An ogival window will have the finest proportions, if the part we name cylindroid has a height of three times its diameter. It will also be well proportioned, if it has E 2 54 PRIMARY FORMS. diameter at the summit, relatively to the base. The one is the cone reversed, the other the egg reversed—the small end downwards; we might also call it reversed ogivoid, which we no more approve of than reversed ovoid for ogivoid. The ovoid is one of the forms most employed in the Ceramic art of the Greeks. The ruins of Nola, Vulci, Tharros, Polentia, Milo, Samos, &c., have opened to us the most ancient products of Greece and Etruria. Tombs filled with ceramic offerings, the last testimony of the affection and recognition of the living for the dead, of a parent, child, friend, benefactor, or inaster, have been brought to light. Vases of the most varied forms have been exhumed. We may perceive that the ovoidal form, with large mouth, was, if not the most used, at least the most regarded, since it was reserved for the highest honours, and for the finest works of the ancient potters. Among the Athenians, the Panathenian vase, filled with the oil of the sacred olive, and awarded to the victors in the solemn games, was ovoid, with straight neck, of well proportioned length, and discoid mouth. Its elongated ovoid rested upon a foot formed of two discs of unequal diameter and thickness. The verses of Pindar, as well as the Greek medals, have immortalized the Panathenian vase. A general observation results from the examination of collections of antique vases, and from this observa- tion we deduce a precept useful to Ceramic art. Among ovoids, some have large mouths, others straight necks. We may remark that generally, the larger the mouth, 56 PRIMARY FORMS. truly beautiful, whatever may be the beauty of its con- tour, and of its ornaments. If the neck is twice as high as the vase, a good abnormal effect may result. If the body is twice, or three times as high as the neck, the law of proportion is satisfied, taking into considera- tion the principle above stated. The ovoid, as we regard it, is a form exclusively Ceramic; it has no significance in architectural con- structions. The domes of St. Peter's at Rome, of St. Paul's at London, of the Panthéon at Paris, generally regarded as ovoids, are sublime ogivoids. As an ornament in architecture, the ovoid, under the name of egg, is frequently and usefully employed in entablatures and eurythmic compositions; it corres- ponds agreeably with the modillions and dentels, which it embellishes by contrast. Considered alone, the egg ornament also produces a good effect by the interposi- tion of slender lines and acute forms. The eggs of the Temple of Concord are intermixed with points. In the Temple of Jupiter Tonans, the arrrow-point contrasts with the curve of the egg. Finally, we see that the ovoid has been chosen by the Creator for the form of a young and beautiful face. This consideration, which is a law of general beauty, explains the success of the ovoid vase and the beauty of the egg, for man esteems above everything the contours which reproduce his own image. 60 MIXED FORMS. things from the Egyptians, 'but the latter, in their turn, owe much to Indian traditions. The design representing the Cano- FIG. 3. pian form, A, and the Phocian form, B (these two mixed forms par excellence), superimposed, will render apparent, much better than a long discourse, the influence of the contours of the human form upon our predilections and judg- ments in producing Ceramic forins of abstract form and beauty. These forms have been indicated (Frontispiece, D 1, E 1), as the types of the mixed form; the first, A, having given rise to the contours of the Doric capital of the most beautiful Greek temples, was consecrated by Phidias, either in the torus of the Parthenon,. or in the portion of the frieze where we see four amphoræ, found in the ruins on the north of this temple. The second, B, has produced the capitals of the temples of Elephanta, of Karnac, and also a form of the most ancient supports of the Indian temples. This design, A B, far from being the result of subtle research, or of slight analogy, represents, in an analytical point of view, a profound and important observation. As to the truth of these analogies, they will be demonstrated to the reader who attentively examines the Egyptian antiquities collected in the British Museum and elsewhere. aliwa 62 COROLLÆ, CAMPANULÆ, AND STEMS. art, shines with all the beauty of a field flower, and alone, without ornament, without any addition what- ever, forms an elegant vase. When the curvature of the sides commences at the lower third (Frontispiece, F 2), the form, approaching more that of a clavoid, without ceasing to be beautiful, requires less height relatively to the diameter, and now the want of a base begins to appear evident. This second corolla is that which forms the sides of the composite vase called the Medician. Lastly, when the cylindroid is inflected outwards, com- mencing with the upper third, and inwards, commencing with the lower third (Frontispiece F3), this mixed form, which is that of a bell, is called campanula. It resembles the flower of the lily of the valley; but stability requires that the campanula should have a base, or a foot. Considered by architects as an integral part of the Corinthian capital, the campanula goes back to the epoch at which Callimachus lived; and, as a ceramic work, having preceded the capital of Callimachus, its origin is lost in the darkness of ages. We may regard the stems, or elongated corollæ, in Ceramic art, as members of a composite work, or as ex- ceptions which fancy can oppose to the rigorous prin- ciples of art, but which good sense and good taste admit only when provided with members which ensure their stability. The intimate union of the straight line with the curved line in the same contour, is the principle which must preside in tracing corollæ, campanulæ, and stems. 68 MOULDINGS. but its effect will especially depend upon the law of proportions (p. 28), by means of which a mass governs the details which are subordinated to it in volume, in light, and in importance. This law being unknown or misunderstood, a suc- cessful moulding is the result of accident; and in almost every edifice, we perceive the uncertainty that prevails in this particular. FIG. 6. If we analyse the profile of this torus, which is only a simple circular moulding, we find a straight line B A governing by its extent the curves B C and A, which are attached in unequal quantities, in place of a quarter circle as used by the Romans and the Italians Vignola, Palladio, and Sca- mozza, and in place of the PROFILE OF THE CAPITAL OF THE mouldings of the carpenters of all times; we see the intelligent application of the finest and profoundest arcana of the science of forms; the mixture, in certain quantities of plane and curved surfaces in the same contour. Let us examine a moulding among a thousand, that of a structure dating from the finest period in Ancient Art, in order to demonstrate the little use made of the compass by the great masters of architecture. The rounded parts E D of this moulding, are re- markable in this-their contours, as those of the COLUMNS AT ELEUSIS. LAWS OF ORNAMENTATION. tions results from the complication of the relative parts, from the contact of the different members composing the whole. Strength and weakness, order and dis- order, symmetry and non-symmetry, cross, bind, and unite to form unity from variety. The beauty of an ornament, of a theorem in geo- metry, of a dramatic, oratorical, or musical composi- tion, depend on the same law. The word complication suggests the idea of order, of clear solution, and, at the same time, of obscure combination; it indicates at once the knotting and the unknotting; lastly, and always, diversity and union. As to beauty, which acording to Diderot, resides in “a word, an idea, a part of an object,” to which we see nothing analogous in archi- tecture, it corresponds to a primary or mixed form : it has its particular law, which is the law of fitness. Complication is also a phase of art, which is derived from the sentiment Dedalus has expressed in the plan of his labyrinth ; Solomon in his mysterious seal; the Greeks in their interlaced meanders; the Byzantines, the Moors, and the architects of our cathedrals, in their most beautiful works. The interlacings, the mosaics, the intersection of ribs and fillets, are the results of complication. Complication charms us, in presenting to our notice the material formula of intelligence in labour; of in- telligence combining without separating the different or opposed parts of a whole. Complication, considered as a work, and as a prin- ciple, is a visible glorification of the human mind, raised to divinity by the infinite perception of regular REPETITION. 75 of a melody. We admire the beautiful arrangement of the consecutive metopes, the regularity of their periodi- cal movements, the proportion of the intervals, the accuracy of the time, the perfect harmony of the concerting parts—I say, concerting, for the object of eurythmy is the uniting in a general concert the varied members and ornaments of an edifice. If we approach nearer, we perceive the mouldings and their reliefs, the meanders which harmoniously roll and unroll themselves, in spaces at learnedly cal- culated distances; heads of growling lions, the salient forms of which are spirited notes in the midst of crepi- tant palm-leaves; the flutings of the columns appear like the vibrations of the male voice; the capitals, by their rounded form, convey to the mind an impression of the lugubrious drum—they contrast, in their re- sonance, with the large triple band of the architrave, which extends like the line of a long recitative, and combines the unequal tones of a monumental concert in a unity. Such effects are not due to a capricious imagination ; they proceed from science-- from a law - from eurythmy. They explain why music formed a part of the education of an Athenian architect, the possessor of the secrets discovered by Pythagoras. III. REPETITION. Repetition is justly considered as one of the principles of ornamentation. A common-place object-a small cube, for instance-being repeated, and formed into a 76 ALTERNATION AND INTERSECTION. continuous series, produces an agreeable effect in a moulding; such are dentels. A channel, a leaf, &c., being repeated, become architecturic ornaments, which derive all their value from repetition. The Corinthian order demonstrates this truth in its minutest details. IV. ALTERNATION. Repetition may be simple as just described, it may also be alternating when, for example, the spaces between the leaves of ivy on a moulding, are filled with leaves of another kind, elongated, for instance, the pointed form of which produces alternation : or when square discs or rings are placed between elongated pearls, or when the egg or ovolo is repeated alternately with a leaf or dart. Alternation is a formula of repetition, which has its rule; this rule is, that the alternating parts must vary in volume and in extent, as well as in form and in design. Symmetry and variety, repetition and in- equality are the rules, the principles of alternation. V. INTERSECTION. The Greeks, in the ornamentation of a moulding, had recourse only to repetition or alternation: imitated by the Romans, who, in their turn, are imitated by the moderns, we must not be surprised that words are wanting to express unknown facts. It then becomes necessary to employ the word intersection, to designate the extension of an eurythmic cadence, and the beats