548. The applications I propose to make are of two kinds: the one relating particularly to the arrangement of plants in gardens, according to the colour of the flowers; the other, to the method of distributing and planting ligneous plants in masses, which I suppose to have been previously planned. Doubtless, I need not have discussed the latter subject, but I have been led to it so naturally, and the rules which guided me are so positive and simple, that I have no doubt of their proving profitable to those of my readers who follow them in laying out plantations, &c.

The artist who conducts these operations is called a Gardener, or Landscape Gardener.

ON THE ART OF ARRANGING ORNAMENTAL PLANTS IN GARDENS
SO AS TO DERIVE THE GREATEST POSSIBLE ADVANTAGE
FROM THE COLOURS OF THEIR FLOWERS.

549. Among the pleasures afforded us by the cultivation of choice plants, there are few so intense as the sight of a collection of flowers, varied in colour, form, size, and position. It is probably because we admire the plants individually, and become attached to them on account of the pains they cost us, that we have hitherto so generally neglected to dispose them in such a manner as to produce the best possible effect when their flowers are seen collectively.

Thus, no defect is more common than that of the proportion in which flowers of similar colours are distributed in a garden. Sometimes the eye is struck by blue or white, sometimes it is dazzled by yellow. Add to this defect of proportion, the ill effect produced by placing together many species of flowers, which, although of the same colour, are not of the same tint: for instance, in spring we see the leopard’s bane (doronica), of a brilliant golden yellow, side by side with the narcissus, which is of a pale greenish yellow; in autumn, the Indian pink beside the African marigold, dahlias of various reds grouped together, &c.

Such arrangements as these cause the eye, accustomed to appreciate the effects of contrast of colours, to feel sensations quite as disagreeable as those experienced by the musician whose ear is struck with discords.

550. Previously to my observations on simultaneous contrast, and the demonstration of the law which governs it, it was impossible to prescribe rules which, by instructing horticulturists to place, with certainty of success, flowers in proximity whose colours reciprocally enhance each other, enabled them to avoid either the monotony resulting from the grouping of flowers of the same colour, or the disagreeable effect of a collection of flowers whose hues are mutually injurious.

ASSORTMENTS OF FLOWERS,

Where the Plants are apart.

551. The associations of flowers which relate to the harmonies of contrast of colour, are first, those with colours mutually complementary to each other; such as blue with orange, or yellow with violet. Rose or red flowers contrast with their own leaves.

552. White flowers accord more or less favourably with blue and orange flowers, already allied together; and perfectly with rose or red flowers, but not so well with yellow or violet flowers, already allied. White associates much less favourably when the latter is brighter or greener.

White flowers are the only ones that possess the advantage of heightening light tones of any colour, and of separating those whose colours are mutually injurious.

553. Yellow flowers, especially those which incline to orange, accord very well with blue ones.

Flowers of a yellow, more green than orange, have a very good effect with flowers of a red inclining to blue, rather than to orange.

Deep red flowers accord well with deep-blue flowers.

Orange flowers are not misplaced near violet flowers.

ASSORTMENTS RELATING TO THE HARMONIES
OF CONTRAST OF HUES.

554. It is so difficult to make associations of hues which will have a satisfactory effect, that I prescribe in general the mutual association of flowers whose colours belong to neighbouring scales.

We must then separate

Where the Plants are indiscriminately mixed.

555. Flowers which only present contrasts of hues and which spring from seeds sown thickly in borders, or in beds, will not have the same objection as when the roots are planted at a distance from each other.

556. Flowers, presenting a disagreeable contrast of hues, may still produce a good effect, when their assortment makes part of an arrangement of contrasts of colours, strongly opposed; in this case being no longer seen isolated, they become in a manner the element of a picture.

Section II.

ASSORTMENTS AS TO HARMONY
OF ANALOGY.

557. I only reckon shrubs susceptible of this harmony; because only perennial plants afford to the horticulturist a guarantee that the flowers of one year will be identical with those of the preceding; consequently, if we plant woody shrubs in such manner as to secure a regular gradation of tones, the successive annual flowerings will be constantly according to that order. We may apply this kind of arrangement to standard roses.

558. But I do not advise any one to attempt submitting annuals to this arrangement, because of the uncertainty that exists in the tones of their colour.

Harmonies of Analogy of Hues.

559. If I have spoken against the associations of contrast of hues (554), I am more inclined to speak against the associations of analogy of hues, always remembering the restrictions I have stated above (Section 1). We must not forget that my intention is to describe assortments, whose good effects are certain. Now the more the colours contrast, conformably to our law, the more latitude there will be, although the colours of individual flowers associated vary in tone and in hue.

560. An objection might be addressed to me that the green of the leaves, which serves as a ground to the flowers, destroys the effect of their contrast. But it is not so; and to be convinced of it, it is sufficient to fix upon a screen of green silk, two kinds of flowers in conformity with the arrangement of the coloured bands (pl. 1. fig. 7), and to look at them from a distance of about ten paces; for when the eye is fixed on two well-defined objects simultaneously, surrounding objects, especially distant ones, produce but feeble impressions.

ON THE ART OF ASSORTING LIGNEOUS PLANTS IN GARDENS, SO
AS TO DERIVE THE BEST POSSIBLE ADVANTAGE FROM THE
COLOUR OF THEIR FOLIAGE.

561. If we consider trees and shrubs no longer under the relation of the colour of their flowers, but with regard to the manner in which we may employ their foliage in the decoration of gardens, we shall perceive that there is only a very small number of contrasts of scale and hue which we can realize while vegetation is active; yet in autumn, when plants, losing their leaves before falling, assume various colours, as red, rose, scarlet, orange, and yellow, these, by their brilliancy, recall the season of flowers. Most trees and shrubs present, in the summer season, only the green of their foliage; and, although this green varies in tone and hue, the differences are always trifling.

562. Harmonies of Contrast.—The most decided contrast of colour that we can establish between the leaves of ligneous plants, is that of green, with foliage nearest to red. But even the purple beech is more of a red-brown than a dark red, properly so called, for the colour of leaves results from a mixture of red and green, which, according to the principle of mixing colours must produce black, if they are in suitable proportion, or a brown tone of the green or red scale, according as one or the other colour predominates. The contrast of hue is established by the assortment of a bluish-green and a yellowish green of tones unequally high, by the contrast of a bluish-green brown with a yellowish light green, &c.

563. Harmonies of Analogy.—Nearly all the masses of various trees in our landscape gardens present certain harmonies of hues mostly resulting from associations established according to considerations foreign to those of the assortment of foliage—an evident result, remembering (561) that the colours of the leaves of the greater part of plants are of green belonging to scales more or less allied, and of tones but little distant from each other.

ON THE DISTRIBUTION AND PLANTING
OF TREES, ETC., IN MASSES.

564. The principal object of the two following chapters is to supply a deficiency in works on gardening as to the manner of distributing and planting trees in masses, &c., the outlines of which have been previously sketched conformably with precise rules. For authors say nothing on this subject, and the embarrassment of a landowner who wishes to plant an estate already planned out, is further increased by this circumstance, that, in the majority of cases, the author of the plan of the projected garden, after having defined the lines of the plantations, indicated the places where isolated trees must be placed, designated the kinds of trees which should constitute groups, and others which must enter into the formation of masses with trees and shrubs (which he does not generally indicate), leaves the care of planting and other details to ordinary gardeners.

Yet the distribution of trees and shrubs, however easy it may appear, in a piece of ground otherwise perfectly planned, contributes more than is generally supposed to the pleasure of a landscape garden, and presents also more difficulties than to allow of its being effected in a satisfactory manner, when it is abandoned, as generally happens, to chance. In fact, if, at the end of a few years, we observe the greater part of masses planted as they frequently are, we shall be struck with defects which were not at first perceptible, because we were then under the influence of the pleasure we always experience at witnessing the development of plants which have been confided to a carefully prepared soil; and besides, there are some defects which are only perceptible after a certain time, such, for example, as that resulting—

1. From the plants being placed too near together.

2. From placing, in the front row, clumps which rise too high, or which lose their lower branches. Such are the elder tree, and sumach.

565. It was after many years of lost enjoyments, through having planted without fixed rule, masses otherwise well designed in their contours, that I was led by my own experience to seek the means of avoiding similar errors in future. The rules I now give are not the result of reflection merely; they have been practised many years, and I am much deceived if those who observe them will not derive great facilities in their application, and experience from them a lively satisfaction.

566. I will now define several expressions employed to designate the different associations of plants which may form part of a landscape garden.

An assemblage of trees and shrubs, occupying a large space, is termed a forest. But in a landscape garden a similar assemblage, or that which has been arranged to present the appearance of a vast space, is called a wood, if it is composed of trees and underwood; and a park, if it consists of trees only.

A collection of trees, shrubs, bushes, and underwood, is called a grove; when it consists only of trees, it is termed a group of trees.

There are thickets of shrubs, bushes, underwood, and of flowering herbaceous plants.

There are thickets formed of a single species of plants, and thickets formed of several species. The first are called homogeneous, and the second heterogeneous, or varied.

There are isolated masses, and masses subordinated together.

A small mass of flowers or shrubs, isolated, and of a circular or elliptical form, is called a bed.

CHAPTER I.
Of Lines of Plants.

567. I call a line of plants, plants placed at equal distances from each other, in straight or curved lines: these plants may be trees, shrubs, bushes, underwood, or flowering herbaceous plants.

568. A line of plants of sufficient extent, and of which the plants are close enough to conceal from view objects placed behind them, is called a screen.

All masses planted according to my method are composed of lines of plants parallel to each other; in other words, there is between two similar lines an equal distance throughout. But the distance between the first and the second may differ from the distance between the second and the third, and so of the others. The result would be the same if the lines were closed curves, as, for instance, circles or ovals. The lines of plants are the elements of the masses.

Article I.
Of the Lines of Plants called Screens.

569. When we desire to conceal any object of considerable extent, we have recourse to a screen of plants. Whenever the extent of the land will not permit of the planting of several lines, constituting a mass, evergreens, such as thujas, almond-laurels, &c., are those to be preferred, succeeded by the hornbeam, lilac, privet, &c.

The most homogeneous screens, that is to say, those which are formed of a single species of plant, are preferable to all others for the object they are intended to fulfil; and to avoid the monotony of a single species, we must have recourse to one which offers varieties. For example, a screen composed of violet and white lilacs, will possess at the same time the advantage of homogeneity for concealing what is behind it, and the advantage of variety of foliage; the leaves of the violet-lilac being of a less yellow-green than those of the white lilac. We may alternate one or more plants of violet-lilac with one plant of white lilac.

Of Lines of Plants considered as
Elements of Masses.

570. 1st. If the plants in the same line are not of the same species, it is essential that they do not differ too much from each other in respect to height.

2nd. Where a line happens to be entirely seen, the same species must be placed alternately.

3rd. We must avoid placing the same species in two neighbouring lines, when we would employ varied masses which are composed of several lines only.

Rule.—When two lines of vegetation are planted to constitute a mass, in planting the first or exterior line, we must follow the rule indicated above (570), then go on planting the second line, in the same manner as the first, except that the stakes indicating the centre of vegetation must be placed chequer-wise relatively to the centre of vegetation of the first line.

I will cite an example of a plantation of two lines intended to conceal a wall.

1st Line. 1. Almond-laurel. 2. Violet-lilac. 3. Laburnum. 4. Violet-lilac. 1a. Almond-laurel, &c.

2nd Line. 1. Clump of prunus mahaleb. 2. Idem, &c.

The distance between the clumps of the first line is four or five feet.

We may plant the first line in screen, and the second with trees larger than in the first; we may also plant the second line with roots of prunus mahaleb, comprehending between two roots three or five clumps of the same species.

Of Homogeneous Masses.

571. The homogeneous mass includes only a single species of plant, because the intention of the gardener in forming it, is to produce an effect of individuality.

In the large French garden, designed by Le Notre, where the trees combine so effectually with the elements established by the architect, to prolong, so to speak, a similar work, the symmetrical plantations are identical, and generally composed of trees of a single species.

572. Although homogeneous masses of trees have a good effect in a large composition, it is not so with those which are composed of a single species, or of a single variety of flower. They almost always present a monotonous aspect, especially if the latter have a definite extent; and if the species of plant of which they are composed is in flower only a part of the year, the defect of monotony will be greatly increased. Homogeneous masses of shrubs or of flowers are only suitable when they are in leaf or in flower during a great portion of the year; as their extent is small, and they serve simply as a bond of union between different parts more or less distant from each other.

Of Heterogeneous or Varied Masses.

573. I shall distinguish two cases—one where it is a heterogeneous or varied mass, isolated, intended to serve as an individual composed of distinct parts; and the other where it consists of many varied masses, allied together, and separated by paths, at least in some parts.

Isolated Masses.

If each line consists of only a single species, we must arrange the lines according to their size. For example—1. Lilacs. 2. Laburnum. 3. Judas trees.

574. Heterogeneous or varied masses placed together so as to form a whole, are generally separated from each other by glades, or unplanted intervals, but cultivated or sown in grass, or by paths. To make what follows thoroughly understood, I must point out the essential difference that exists between landscape gardening and French (geometrical) gardening.

575. French gardening is regular and symmetrical, the paths are straight, and the eye is only impressed by objects slightly varied; for when there are squares or straight borders, symmetry necessarily requires that the objects on one side be repeated on the other. The result is, that when the spectator has visited the principal points of this composition, which are never very numerous, he has seen everything it has to offer to his curiosity.

576. I will not say, with some writers, that landscape gardening is conceived with an entirely different aim. The spectator who surveys a landscape garden, should be excited, so to speak, at every step, by the sight of various objects. The different points of view must be as numerous as possible, the paths must always, therefore, be traced, so that from no point can their whole extent be discovered. The plantations must be disposed so as to conceal the walls, fences, or other disagreeable ill-placed objects. They must allow the eye the greatest possible scope, at all the points the gardener wishes to be displayed; and the views must vary with the different points successively observed.

577. To achieve this, it is evident that there must be no straight paths, but only curved ones. When paths pass between masses, the intervals between these masses must also permit to be seen groups of objects, which must form planes, skilfully prolonging the perspective, as far as possible. The masses, though varied, must nevertheless be allied together, so that neighbouring masses may harmonize as dependent parts of the same whole.

Article II.

578. Harmony between masses distant from each other, in which harmonies may be established by the same general means as they are between neighbouring masses. The foliage in the masses being much more abundant than the flowers, the shades of their greens will not differ so much from each other as the colours of their flowers; consequently, the distant masses, however varied in their foliage, are always in harmony of form and colour, if they have been planted according to our rules; and if they are composed solely of ligneous plants, which lose their leaves in winter, or solely of evergreens, which do not lose them; but in the opposite case, that is to say, when the masses are formed, the one of deciduous trees, and the other of evergreens, some remarks must be made relative to the conditions of harmony, which are the more necessary, as even the most studied landscape gardens generally err in this respect; for a clump or a mass of evergreens is almost always out of keeping in a large space where masses of deciduous trees are found. To remedy this defect we must multiply the groups or masses of evergreens, so as to establish between all of them this same correlation which is required by deciduous trees; but it is not necessary that the trees should occupy a space equal to that occupied by ordinary trees; it is sufficient if their forms recur at suitable intervals. In a word, for evergreens to produce a good effect, they must compose a whole, which unites or intercalates with the general effect of the masses of deciduous trees.

We may oppose allspice trees to pines, cedars to larches; different groups, composed of three or four trees only, suffice to harmonize a large space of ground occupied with two or three groups composed of half a hundred similar trees.

579. There are certain cases in which the want of either perspective or harmony requires, in a large mass, a line of trees which is neither concentric with its circumference, nor identical with the central line, if there be one; such, for example, as the line P. R., which is found in the masses 1 and 2 (Pl. 18); for if the planting of this line be correct, and according to the preceding principles, the trunks, which define it, beyond the concentric plantings, must be in the points of intersection of the line P. R., with the concentric lines, and the central line, if there be one; and the trunks must be as much as possible at equal distances from each other.

Such a plan, always easy to make, will enable a landowner, when once his masses are planned, their concentric lines traced, and the species to be planted determined upon, to order from the nurseryman the exact number of each species he requires.

580. After tracing the lines of plantations, and putting in the stakes to mark out the centre of the holes to be dug, we must draw upon grey paper lines representing those of the masses we intend to plant, taking as many equidistant points as there are stakes in the corresponding lines of plantation; we then fasten on these points wafers, or little circles of paper, of the colour of the flowers or the foliage of the plants, according to the desired effect.

By this means we can judge of the harmony of the colours of flowers with the different hues of green composing the mass, and thus rectify any defect in the plan before we begin to plant.

The principles on which the preceding rules are founded are those of height, form, variety, facility of development, and distinctness of view. Harmonious arrangement, with reference to these points, not being so exclusively the object of this work as the subject of colour, must be passed with this indication.

Contrast of Colours.

581. This principle, regarded generally, is included in the preceding, since a difference in colour will render plants distinct which have numerous analogies; but viewed specially, it produces among perfectly dissimilar plants, effects which can only be obtained from colour; and it is then that the principle of contrast is to be taken into consideration.

In the application of the law of contrast to the arrangement of flowers, we must never forget the difference between an assemblage forming a line of plants, and an assemblage of flowers belonging to plants of various heights, standing on different planes, so as to produce the effect of a picture. I have alluded to this before (551); for in a linear arrangement, for example, there is nothing more unpleasant than the blue flowers of the German iris, associated with the light violet of the lilac. But if we add to this association large tufts of alyssum saxatile, Persian iris, and red tulips, so that the golden yellow, white, and deep red, appear on one plane, and the deep blue and the light violets on a more distant plane, we shall obtain general effects of a most agreeable kind.

Repetition.

582. When a line of plants exhibits the repetition of the same species, and presents them regularly at the same intervals, an effect is produced which, although very agreeable, is but little appreciated—for it is very rarely met with in gardens. It is especially the repetition of a similar arrangement of colours that is agreeable, and which recommends the observance of this principle.

Repetition of the same arrangement of plants of various kinds, and of course distinct to view, contributes greatly to prolong the extent either of an alley or of a mass; a similar general effect repeated a certain number of times becomes a standard, by means of which the eye judges the space to be greater than if it were bordered with individuals of the same species or variety equal in number to the former. This effect is carried to the utmost extent when the arrangement is composed of a certain number of tufts—five, for instance—placed between two trees, which rise above them, but not too high.

Repetition and distinctness of view concur in producing an agreeable effect.

583. Variety, like every other principle, should never be carried too far, and it is a great mistake to suppose that plantations made without design, and which thus it might seem must be extremely diversified, produce in this respect more effect than those which have been arranged according to the principles of distinct view, contrast, and repetition.

Whenever objects must have a certain superficial extent, we gain nothing by multiplying varieties of them. Thus, the repetition of an arrangement of three colours, including white or black, will generally be more agreeable than that of an arrangement of five colours.

Diversity of colours, pushed to the extreme, can only be permitted in a continuous border, or a bed of different varieties of the same species of flowers, as a border of larkspur, china aster, or anemones; but, for flowering shrubs, we shall gain everything by not indefinitely multiplying their colour, in a view which the eye can embrace at once. And as with colours so with forms, which must not be too diversified in the same arrangement.

Symmetry.

584. We should deceive ourselves very much if we supposed the principle of symmetry to be excluded from landscape gardening. But, in order to perceive it or to put in practice, it is necessary to distinguish the symmetry of similar parts, and the symmetry of parts merely corresponding.

The former is that of two equal parts of one whole, as the two halves of a circle, of a square, of an equilateral or isosoceles triangle, &c.; while

Symmetry of parts merely corresponding, is that of two parts of the same whole, which, without being equal, have the same form, or nearly so; such are the two triangular parts of the Mass 3, Plate 18.

Or, that of two separate parts, more or less analogous in form, extent, or nature, which have a correspondence of position relatively to an intermediate object.

Or, that of two masses or groups of trees, or of a mass and a group of trees which are presented, the one to the left, the other to the right.

General Harmony.

585. In the general composition of a large landscape garden, it is not enough to have satisfied all these principles, if the different masses subordinated together, which we shall now regard as individuals, as well as the various constructions of wood or of stone, are not combined by some harmonious relation suitable for satisfying the principles of general harmony. The isolated or subordinated masses near or distant from each other must be allied together by the same vegetable form or by analogous forms, or by the same arrangements of several species; or, lastly, by the same colours of flowers or of foliage. By the aid of similar means, we ally the house and other buildings to the different parts of the garden. When the neighbouring masses, especially those formed near buildings, are not sufficiently allied together, or the perspective of their concentric or median lines is not satisfactory, we have recourse to a different line of vegetation, which cuts the first and thus adds to the general harmony. Thus, as I have so strongly insisted, when we decide to plant evergreens in a landscape garden, they must be distributed throughout the composition.

SIXTH DIVISION.

586. In this division my object is purely critical. The positive conclusions at which I have arrived upon certain assortments of colours, so as to derive the best result from them under given circumstances, become rules, adapted to guide those who would judge a work of art in which such assortments occur. The generalizations established in the preceding chapters, with the object of aiding the numerous artists who use colours, now critically considered, will serve as the basis of a conscientious and sound judgment upon the merit of any work in which these generalizations are concerned. They will, I trust, possess the double advantage of all the rules involved in the nature of such things; they guide the workman who does not disdain them, and they direct the critic who judges the work of which these rules govern some element. We cannot then refuse to recognise the utility of such an examination, both for artists and for the public, to whom they are more particularly addressed, in the hope that a clear demonstration of what is laudable or censurable will form such a public taste as, by preventing a reliance on first impressions, will lead to a sound judgment; and that we may not henceforth strive to enlist public suffrages by falling into unsuitable singularity, or by wandering from the truth.

587. If there exists a subject worthy of being studied critically on account of the frequency and variety of the cases it presents, it is unquestionably this; for whether we contemplate the works of nature or of art, their varied colours form one of the finest spectacles man is permitted to enjoy. Hence the desire of reproducing the coloured images of objects which excite our admiration or interest, has produced the art of painting. The imitation of the painter’s works has given birth to tapestry, and carpets, and mosaics; while the necessity for economically multiplying designs has led to ornamental printing. The love of colour has also induced man to paint his dwelling and to dye his garments and household decorations.

588. The sight of colours, so simple a thing for the greater part of mankind, is, according to some philosophers, a phenomenon entirely out of the domain of positive knowledge, inasmuch as they consider that it varies with the organization, and even the imagination, of individuals; consequently, they think that it cannot be inferred that, because one man sees an object in a certain way, another will see it in like manner under the same external circumstances. They believe that no generalization, deduced from observation, can direct the artist with certainty, either in the art of seeing his model or in faithfully reproducing a coloured image of it: they also think that no useful physiological generalization can arise from a profound study of the modifications his organs experience from the sight of the colours that bodies present to him.

I cannot admit that we ought to abstain from the study of a subject because it presents variable phenomena.

All those who are engaged in the study of the positive sciences, should inquire for some fact capable of illustrating the study of these phenomena.

589. I entered upon this study, not having spontaneously chosen it, but because it appeared to me indispensable before pretending to establish a sound judgment on the beauty of the dyer’s colours. As soon as I felt the necessity for this study, in my capacity of Director of the Dyeing Department of the Royal Manufactories, my first care was to discover whether I saw colours as the generality of persons see them. I was soon perfectly convinced that I did, and not till then did I venture to make my researches the subjects of public lectures. These have been repeated before the students of the Polytechnic School. Certain questions addressed to my auditors to satisfy me that they saw the things I put before their eyes as I saw them myself, have, in the majority of cases, always proved them to be so, and yet my demonstrations were given in the reception-hall at the Gobelins,—a place ill adapted for the exhibition of the phenomena of contrast to a large audience. Certain observations by myself, tested by a great number of persons in my laboratory, and afterwards publicly exhibited, form the subject of this book; all who repeat my experiments will discover whether my opinion is well-founded, or whether an opinion is correct which pretends that the sight of colours is not capable of giving a general positive result. Because some individuals have organs of sight so imperfect that they cannot distinguish green from red, or blue from grey, &c., must we write our treatises on optics without mentioning either red, green, or blue, and cast away these colours from the palette? Assuredly human nature is too limited to allow of our making such a sacrifice of our common organization to the infirmity of an individual.

590. In order to comprehend clearly how experiment and observation, after having disentangled the causes which exercise a determinate influence upon the sight of colours, led me to adopt the opinion that these phenomena are perfectly defined by the law of contrast and the conclusions therefrom, doubtless it will suffice to consider how

1. Our former ignorance respecting the different states of the eye, which, in seeing colours, give rise to the phenomena of simultaneous, successive, and mixed contrasts.

And our former ignorance respecting the definite influence that the direct or diffused light of the sun exercises, according to its intensity, upon the colours of bodies, have led to the establishment of an opinion contrary to my own;—that is to say, the opinion that the same colour appears so diversely to different persons, and even to the same person, that nothing general or precise can be deduced from the sight of coloured objects, with regard to their respective colours.

2. To consider how the following have passively contributed to belief in this opinion.

The limited number of ideas we have generally about the modifications of coloured bodies, by their mutual mixtures; or in other terms, upon the colours resulting from these mixtures.

The want of a precise language to convey the impressions we receive from colours.

591. It is indisputable that if we are ignorant of the regularity with which the eye passes successively through stages, the extremes and the mean of which are very different, in viewing the colours which put the organ into the condition of perceiving the phenomenon of one of the three contrasts (77) we shall be led to consider the sight of colours as a very variable phenomenon, while the successive stages through which the organ passes being once distinguished, the variations of the phenomenon become perfectly definite.

592. If we are ignorant of the law of simultaneous contrast, we shall suppose that the same colour varies in tint according to the colour with which it may be associated; and if we are ignorant that contrast affects the tone as well as the colour, we cannot explain how two similar colours (for instance, blue and yellow at the same depth of tone) will appear redder by juxtaposition; while, if the blue is very deep relatively to the yellow, it will appear black, rather than violet, and the yellow will appear more green than orange. Finally, if we are ignorant of the effect of the brightness which a complementary can give to a dull colour, we cannot explain the great difference there is between the effect that a red ground has upon imitative gilt ornaments, and the effect of the same ground upon metallic gilt ornaments (384).

593. Doubtless, also, if it be not known that in a complex object, the eye can only see clearly at the same moment a small number of parts and that the same part may appear to different eyes with different modifications, according as it is seen juxtaposed with one or another colour, as in the instance given (407).

594. We might know the regularity of the successive states of the eye during the sight of coloured objects, and the law of simultaneous contrast of colours, and yet, if we were ignorant of the influence of various degrees of intensity of light in varying the colour of bodies and in rendering the modifications of contrast more or less evident, we should be led to believe in an indefinite variation in the aspect of colours; but this variation is perfectly defined by the following remarks:—

If the direct light of the sun or diffused daylight illuminates a monochromous body unequally, the part most vividly lighted is modified as it would be if it received orange, and the modification appears the stronger the greater the difference of light on the parts (280): thus the more intense the light, the more it gilds the body it illumines; it is thus always easy to foresee the effects of it when we know the result of the mixture of orange with various colours.

595. The phenomena of simultaneous contrast being less evident in a very vivid light than in a weaker light (63), it follows that if we disregarded the difference in the effects, we should greatly deceive ourselves in our appreciation of the phenomena of contrast of similar colours. Simultaneous contrast, which tends to make the differently coloured parts appear as distinct as possible, is carried to a maximum, precisely when the light being feeble, the eye requires the greatest contrast of colour to perceive distinctly the various parts upon which it is fixed.

596. We may perceive the modifications presented by bodies when lighted, and yet we may experience much difficulty in accounting for them, for want of knowing how to represent exactly the modifications which the coloured materials experience, in their colour, according as they receive light or white, shade or black; or according as they are mixed together. It is partly to make these modifications clearly known that I have designed the chromatic hemisphere (134, et seq.). In describing it, I have attached less importance to its material realization than to the rational principle upon which it depends. On looking at the lines of this diagram independently of all colouring, we understand how any colour is reduced by white, deepened by black, and broken by black and white, and how, by mixture with a pure colour, it produces hues. I shall add subsequently some new considerations on the gradations of colour made with coloured materials.

My object would not have been attained had not the chromatic hemisphere given me the means of representing, by a simple nomenclature, the modifications which a colour undergoes by the addition of white and black, modifications which produce the tones of its scale; those which it receives from black yielding broken scales, and those resulting from the addition of a pure colour, produce scales which are hues of the first colour.

597. Finally, to the definitions which I have given of the words tone, scale, hue, broken colours, I must add the distinction of the associations of colours into harmonies of analogy, and harmonies of contrast (172).

I am convinced that all those who accept the small number of definitions I have given, will find much advantage from them in accounting for the effects of colours, and in expressing their views to others. By their aid it will be easy to notice relations which might have escaped observation, or which, in the absence of precise language, could not have been clearly communicated.

598. It would be ignoring a fact to attribute the opinion I have combated, exclusively to ignorance of what I have just recapitulated, or to believe, that in order to establish the contrary opinion, which I maintain, it is sufficient to dissipate this ignorance.

But I am satisfied with pointing out the error, without making the least pretension to overthrow it, otherwise than by stating what I believe to be the truth.

599. The study of the positive facts just reviewed, leads to a certainty in the view of colours which all may acquire who devote themselves to it. They will see how fruitful it is in applications, and that it is independent of every hypothesis, and that it would be impossible to obtain this result, if there did not commonly exist among men an average organization of the eye, which permits them to perceive in similar circumstances the same modifications, but with varied intensity of perception.

600. Having noticed the series of principles upon which my book is founded, I next consider these facts under the three following relations:—