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creases during the following years. At five, the crystalline lenses of Turner's eyes first it can only be perceived by a careful became rather dim, and dispersed the light examination of the picture, but from the more strongly, and in consequence threw year 1839 the regular vertical streaks be- a bluish mist over illuminated objects. come apparent to everyone. This in- This is a pathological increase of an opticreases subsequently to such a degree, cal effect, the existence of which, even in that when the pictures are closely exam- the normal eye, can be proved by the folined they appear as if they had been wil- lowing experiment. If you look at a picfully destroyed by vertical strokes of the ture which hangs between two windows, brush before they were dry, and it is only you will not be able to see it distinctly, as from a considerable distance that the ob- it will be, so to speak, veiled by a greyish ject and the meaning of the picture can haze. But if you

hold hands before be comprehended. During the last years your eyes so as to shade them from the of Turner's life this peculiarity became so light of the windows, the veiling mist disextreme that his pictures can hardly be appears, and the picture becomes clearly understood at all.

visible. The disturbing light had been It is a generally received opinion that diffused by the refracting media of the Turner adopted a peculiar manner, that he eye, and had fallen on the same part of exaggerated it more and more, and that the retina on which the picture was formed. his last works are the result of a deranged If we examine the eye by an illumination intellect. I am convinced of the incor- resembling that by means of which Prorectness, I'might almost say of the injus- fessor Tyndall

, in his brilliant experitice, of this opinion. The word “

ments, demonstrated to you the imperfect has a very vague meaning. In general transparency of water, we find that even we understand by it something which has the clearest and most beautiful eye is not been arbitrarily assumed by the artist. so perfectly transparent as we would supIt may be the result of study, of reflec- pose. The older we get the more the tion, of a development of principle, or the transparency decreases, especially of the consequence of a chance observation, of lens. But to produce an effect equal to an experiment, or of an occasional success. that visible in Turner's pictures after the Nothing of all this applies to what has year 1831, pathological conditions are rebeen called Turner's manner. Nothing in quired. In the years that followed, as him is arbitrary, assumed or of set pur- often happens in such cases, a clearly depose. According to my opinion, his man- fined opacity was formed in the slight and ner is exclusively the result of a change in diffuse dimness of the crystalline lens. his eyes, wbich developed itself during the In consequence of this the light was no last twenty years of his life. In conse- longer evenly diffused in all directions,

the aspect of nature gradu- but principally dispersed in a vertical dially changed for him, while he continued rection. At this period the alteration in an unconscious, I might almost say in a offers, in the case of a painter, the pecunaive manner, to reproduce what he saw. liarity that it only affects the appearance And he reproduced it so faithfully and of natural objects, where the light is accurately that he enables us distinctly to strong enough to produce this disturbing recognize the nature of the disease of his effect, whilst the light of his painting is eyes, to follow its development step by too feeble to do so: therefore, the aspect step, and to prove by an optical contriv- of nature is altered, that of his picture ance the correctness of our diagnosis. By correct. Only within the last years of the aid of this contrivance we can see na- Turner's life, the dimness had increased ture under the same aspect as he saw and so much, that it prevented him from seerepresented it. With the same we can also, ing even his pictures correctly. This suffi. as I shall prove to you by an experiment, ciently accounts for the strange appeargive to Turner's early pictures the appear- ance of his last pictures, without its beance of those of the later period.

ing necessary to take into account the After he had reached the age of fifty-'state of his mind.

quence of

It may seem hazardous to designate a legs, “ You don't understand ; that's just period as diseased, the beginning of which the beauty of it." art-critics and connoisseurs have consid- I show you here first a picture which is ered as his climax. I do not think that copied from an oil-painting in the South the two opinions are in decided contradic- Kensington Museum. This picture was tion to each other. To be physiologically not exhibited till the year 1833, but it was normal is not at all a fundamental condi- painted some time before, and from tion in art; and we cannot deny the legiti- sketches taken in Venice previous to any macy of the taste which regards that which change in Turner's sight. I shall now try is entirely sound and healthy as common- so to change this picture, by an optical place, trivial, and uninteresting, and which contrivance, as to make it resemble the on the contrary is fascinated by that which pictures he painted after 1839. You must, approaches the border of disease and even of course, not expect to see in this rough goes beyond it.

representation, which a large theatre neMany of the best musicians, for instance, cessitates, anything of the real beauty of and some of the greatest admirers of Turner's pictures. Our object is to analyze Beethoven, prefer his latest works, and con- their faults. sider them the most interesting, although In order to show you in a single object the influence of his deafness upon them is what you have already observed in the apparent to others.

general aspect of a picture, I choose purIn poetry, we rank some poems among posely a tree, because there are no trees the highest productions of art in which the in the “ Venice" you have just seen, and imagination of the poet goes far beyond more particularly because after the year the normal region of the mind :

1833 Turner painted trees that were un“ The poet's eye, in a fine frenzy rolling,

known to any botanist, had never been Doth glance from heaven to earth, from earth seen in nature, nor been painted by any

other artist. I do not think it likely that to heaven,”

Turner invented a tree he had never seen; Thus it seems to me perfectly natural it seems to me more probable that he that the peculiar poetical haze which is painted such trees because he saw them so produced by the diffusion of light in Tur- in nature. I searched for them with the ner's pictures after 1831 should have a par- aid of the lens, and soon discovered them. ticular attraction for many of Turner's Here is a common tree; the glass changes admirers. On the other hand, passing it into a Turner tree. over the faults, we discover in these pic- Let us now turn from the individual case tures peculiar merits, and we recognize of a great artist to a whole category of that the great artist continued in many cases, in which the works of painters are ways to improve, even at a time of his life modified by anomalies in their vision - I when his failing sight began to deprive his mean cases of irregularities in the refracworks of general favour. I cannot, how- tion of the eye. The optical apparatus of ever, defend the opinion of those who are the eye forms, like the apparatus of a phoenraptured with Turner's pictures belong- tographer, inverted images. In order to ing to a still later period — who consider be seen distinctly these images must fall a picture beautiful which, in consequence exactly upon the retina. The capacity of of this optical defect, is entirely disfigured the eye to accommodate itself to different and defaced, and who, calling this Tur- consecutive distances, so as to receive on ner's style, would like to form it into a the retina distinct images of objects, school and imitate it. They resemble the called accommodation. This faculty deporter of a certain dealer in works of art, pends upon the power of the crystalline who one day, when he had to deliver the lens to change its form. The accommodatorso of a Venus at a gentleman's house, tion is at its greatest tension if we adapt answered the servant, who had expressed 'our eye to the nearest point. It is, on the his astonishment that his master should contrary, in complete repose if we adapt have bought a thing without head, arms, or it to the farthest point.

The optical

state of the eye during its adaptation for, ridians drawn on the eye as on a globe, 85 the farthest point, when every effort of ac- that one pole is placed in front: then you commodation is completely suspended, is can define astigmatism as a difference in called its refraction.

the curvature of two meridians, which There are three different kinds of refrac- may, for instance, stand perpendicularly tion : firstly, that of the normal eye; sec- upon each other; the consequence of ondly, of the short-sighted eye; thirdly, of which is a difference in the power of rethe over-sighted eye.

fraction of the eye in the direction of the 1. The normal eye, when the activity of two meridians. An eye may, for instance, its accommodation is perfectly suspended, have a normal refraction in its horizontal is adjusted for the infinite distance; that is meridian, and be short-sighted in its vertito say, it unites upon the retina parallel cal meridian. Small differences of this rays of light.

kind are found in almost every eye, but 2. The short-sighted eye has, in conse- are not perceived, Higher degrees of asquence of an extension of its axis, a tigmatism, which decidedly disturb vision, stronger refraction, and unites therefore in are, however, not uncommon, and are front of the retina the rays of light which therefore also found arnong painters. I proceed from infinite distance. In order have had occasion to examine the eyes of to be united upon the retina itself the rays several distinguished artists which preof light must be divergent; that is to say, sented such an anomaly, and it interested they must come from a nearer point. The me much to discover what influence this more short-sighted the eye is, the stronger defect had upon their works. The diversmust be the divergence; such an eye, ity depends in part upon the degree and in order to see distinctly distant objects, nature of the optical anomaly, but its efmust make the rays from a distant object fect shows itself in different ways accordmore divergent, by aid of a concave glass. ing to the subjects the art st paints. An We determine the degree of short-sighted- example will explain this better. I know ness by the power of the weakest concave a landscape-painter and a portrait-painter glass that enables the eye to see distinctly who have both the same kind of astigmaat a great distance.

tism ; that is, the refraction of the verti3. The over-sighted, or hypermetropic cal meridian differs from the refraction eye, on the contrary, has too weak a refrac-of the horizontal one.

The consequence tion: it unites convergent rays of light upon is, that their sight is normal for vertical the retina; parallel or divergent rays of lines, but for horizontal lines they are light it unites behind the retina, unless an slightly short-sighted. Upon the landeffort of accommodation is made. The de- scape-painter this has hardly any disturbgree of hypermetropy, or over-sightedness, ing influence. In painting distant views is determined by the focal distance of the sharp outlines are not requisite, but rather strongest convex glass with which objects undefined and blending tones of colour. can still be distinctly seen at a great dis- His eye is sufficiently normal to see these. tance.

I was struck, however, by the fact that the Hypermetropy has no essential influ- foreground of his pictures, which generalence upon painting; it only reduces the ly represents water with gently-moving power of application, and must therefore waves, was not painted with the same be corrected by wearing convex glasses. truthfulness to nature as the middle and This can never be avoided if the hyper-background. There I found short horimetropy is so great as to diminish the zontal strokes of the brush in different distinctness of vision. Short-sightedness, colours, which did not seem to belong to on the contrary, generally influences the the water. I therefore examined the picchoice of the subject of the artist and also ture with a glass, which, when added to the manner of its execution. As a very my eye, produced the same degree of assmall handwriting is an indication of tigmatism as existed in the painter's eye, short-sightedness, so we find that artists and the whole picture appeared much who paint small pictures, and finish more beautiful, the foreground being now the details with great minuteness, and, as perfect as the middle and back-ground. with fine touches of the brush are mostly In consequence of this artificially-produced short-sighted.

astigmatism, I saw the horizontal strokes Sometimes the shape of the eye diverges of the brush indistinctly and so mixed tofrom is normal spherical form, and this is gether, that through them the colour and called astigmatism. This has only been transparency of the water were most exclosely investigated since Airy discovered quisitely rendered. it in his own eye. Figure to yourself me- Upon the portrait-painter astigmatism

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had a very different influence. He was talent for , painting, drawing alone ought held in high esteem in Paris, on account to be attempted, because so absolute a deof his excellent grasp of character and in- fect will soon assert itself. But we meet tellectual individuality. His adınirers with slighter degrees of colour-blindness, considered even the material resemblance where the perception of red is not entirely of his portraits as perfect; most people, wanting, but only considerably diminished; however, thought he had intentionally so that, for instance, an intense or strongly neglected the material likeness by render-illuminated red can be perceived as such, ing in an indistinct and vague manner the while a less intense red appears green. details of the features and the forms. A This moderate degree of colour-blindness careful analysis of the picture shows that does not always deter people from paintthis indistinctness was not at all intention.ing. A proof of this I saw at the last al, but simply the consequence of astigma- year's Exhibition, in a picture which retism. Within the last few years the por- presented a cattle market. The roofs of traits of this painter have become consid- the surrounding houses were all painted erably worse, because the former indis- red on the sunny side, green in the shadtinctness has grown into positively false ow; but — what particularly struck me — proportions. The neck and oval of the the oxen also were red in the sun, green face appear in all his portraits consider- in the shadow. The slighter degrees of ably elongated, and all details are in the this anomaly, in the form of an insufficient manner distorted.

What is the perception of colours, have probably been cause of this ? Has the degree of his as the real cause why several great artists, tigmatism increased ? No; this does not who have become famous on account of often happen: but the effect of astigma- the beauty of their drawing and the richtism has doubled, and this has happened ness of their compositions, have failed to in the following manner :- - An eye which attain an equal degree of perfection in colis normal as regards the vision of vertical ouring. lines, but short-sighted for horizontal In opposition to these isolated cases, I lives, sees the objects elongated in a ver- have to draw your attention to other cases tical direction. When the time of life ar- which happen more frequently, and in adrives that the normal eye becomes far- vanced age, in consequence of a change in sighted, but not yet the short-sighted eye, the perception of colours. They do not this astigmatic eye will at short distance see arise from a deficient function of the nervthe vertical lines indistinctly, but horizon- ous apparatus of the eye, but in consetal lines still distinctly; and therefore near quence of a change in the colour of the objects will be elongated in a horizontal lens. direction. The portrait-painter, in whom The lens always gets rather yellow at a slight degree of astigmatism manifested an advanced age, and with many people itself at first only by the indistinctness of the intensity of the discoloration is conthe horizontal lines, has now become far- siderable. This, however, does not essighted for vertical lines, and therefore sentially diminish the power of vision. sees a distant person elongated in a verti. In order to get a distinct idea of the effect cal direction; his picture, on the contrary, of this discoloration, it is best to make exbeing at a short distance, is seen by him periments with yellow glasses of the corenlarged in a horizontal direction, and is responding shade. Only the experiment thus painted still more elongated than the must be continued for some time, because subject is seen: so the fault is doubled. at first everything looks yellow to us. But

With regard to an anomaly of sight, the eye gets soon accustomed to the colwhich seems almost foreign to the subject our, or rather it becomes dulled with reof painting - I mean colour-blindness - Igard to it, and then things appear again will also say a few words here, as the sub- in their true light and colour. This is at ject seems to be regarded with particular least the case with all objects of a someinterest in England.

what bright and deep colour. A careful What we call colour-blindness is a con- examination, however, shows that a pale genital defect of vision, which is character- blue, or rather a certain small quantity of ized by the absence of one of the three blue, cannot be perceived even after a primary sensations of colour. The prima- very prolonged experiment, and after the ry sensations of colour are red, green, and eye has long got accustomed to the yellow violet, according to Thomas Young and colour, because the yellow glass really exHelmholtz; or red, green, and blue, ac- cludes it. This must, of course, exercise cording to Maxwell. When, as may easily a considerable influence when looking at happen, to this defect is joined a decided pictures, on account of the great difference which necessarily exists between real ob-pigments as with regard to the blue in jects and their representation in pic-nature. tures.

Imagine now that in the course of years These differences are many and great, one of the transparent media in the eye of as has been so thoroughly explained by a painter had gradually become yellowish, Helmholtz. Let us for a moment waive and that this yellow had by degrees conthe consideration of the difference pro- siderably increased in intensity, and you duced by transmitting an object seen as a will easily understand the influence it body on to a simple Hat surface, and con- must exercise upon his work. He will sider only the intensity of light and colour. see in nature almost everything correctly; The intensity of light proceeding from the but in his picture everything will appear sun and reflected by objects, is so infinite- to him yellowish, and consequently he will ly, greater than the strongest light reflect- paint it too blue. Does he not perceive ed from a picture, that the proportion ex- this himself? Does he not believe it if pressed in numbers is far beyond our told of it? Were this the case, it would comprehension. There is also so great a be easy for him to correct the fault, since difference between the colour of light, or an artist can paint in a yellower or bluer of an illuminated object, and the pigments tone, as he chooses. These are two quesemployed in painting, that it appears won- tions which are easily answered by psyderful that the art of painting can by the chological experience. He does not peruse of them produce such perfect optical ceive it himself, because he does not redelusions. It can of course only produce member that he formerly saw in a differoptical delusions, never a real optical iden- ent way. Our remembrance with regard tity; that is to say, the image which is to opinions, sensations, perceptions, &c. traced in our eye by real objects is not which have become gradually modified in identical with the image produced in our the course of years - not by any external eye by the picture. This is best observed influence or sudden impression, but by a by changing the light. Whoever paints gradual change in our owu physical or in London has but too frequent opportuni- mental individuality - is almost nil. ties of observing this. A little more or He does not believe it - I would not less fog, the reflection of a cloud illuminat- say because an artist rarely recognizes ed by the sun, suffices to alter entirely the what others tell him with regard to his colouring of the picture, while the colour- works, but because with him, as with ing of natural ohjects is not changed in everyone else, the impressions received the same manner.

through his own eye have a stronger Let us now return to our experiment power of conviction than anything ebe. with the yellow glass, and we shall find Sehen geht vor Sagen” (Seeing is jethat it affects our eye very much in the lieving), says the old adage. same way as a yellow tint in the light, and We are almost always conscious of therefore modifies natural objects in quite indistinct vision, be it in consequerce a different degree from pictures. If we of incorrect accommodation or insuficontinue the experiment for a consider- cient power of sight, especially if it able time, the difference becomes more is not congenital, but has gradually apand more essential. As I said before, the peared. But it is extremely difficult and eye becomes dulled with regard to the yel- in many cases impossible to convince low light, and thus sees nature again in those of their defect who suffer from in its nor ral colouring. The small quantity correct vision as to form and colour. They of blue light which is excluded by the yel- never become conscious of it themselves low glass produces no sensible difference, even if it is not congenital and the mos; as the difference is equalized by a diminu- enlightened and intelligent among then tion of sensibility with regard to yellow. remain incredulous, or become even In the picture, on the contrary, there is gry and offended, when told of it. In found in many places only as much blue correct perception of form may, however as is perfectly absorbed by the yellow easily be demonstrated. If in consequence glass, and this therefore can never be per- of astigmatism a square appears oblong ceived however long we continue the ex- to anyone, he can measure the sides with periment. Even for those parts of the a compass; or, what is more simple still. picture which have been painted with the he can turn it so that the horizontal lines most intense blue the painter could pro- are changed into vertical ones, and vice duce, the quantity of blue excluded by the versá, and his own sight will convince him yellow glass will make itself felt, because of his error. It is more difficult to deits power is not so small with regard to 'monstrate whether a person sees colours

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