404 



NA TURE 



\^Mar. 21, 1872 



/?i?. LIEBREICH ON TURNER AND 

 MULREADV 



DR. R. LIEBREICH, in a lecture delivered at the 

 Royal Institution on Friday, the 8th inst., " On 

 the effects of certain faults of vision on painting, with 

 special reference to Turner and Mulready," successfully 

 vindicated the title of physical science to extend its 

 researches into the domain of art criticism by applying 

 optical laws to painting. The lecture may be said to 

 consist of three parts, the first of which demonstrates, by 

 the example of Turner, that there are certain condi- 

 tions of the eye which alter the appearance of nature, 

 whilst they leave the impression a picture produces upon 

 the eye unchanged. The second part of the lecture 

 proves, by the example of a French artist yet living, 

 whose name, therefore, was withheld, that there is another 

 defect of the eye, which produces an incorrect impression 

 of the picture as well as of nature, the error, however, 

 being dissimilar, and aifecting the picture and nature in 

 opposite ways. The third part of the lecture shows, by 

 the example of Mulready, that there is yet another 

 disease of the eye affecting colour.-; in such a manner that 

 pigments used in painting are influenced by the disease, 

 whilst natural colours continue unaltered. 

 I. — Turner 

 Surprised at the great difference between Turner's 

 earlier and later works, said the lecturer, he examined 

 one of the great artist's later pictures from a purely scien- 

 tific point of view, and analysed it with regard to colour, 

 drawing, and distribution of light and shade. 



It was particularly important to ascertain if the anomaly 

 of the whole picture could be deduced from a regularly 

 recurring fault in its details. This fault is a vertical 

 streakiness, which is caused by every illuminated point 

 having been changed into a vertical line. The elongation 

 is, generally speaking, in exact proportion to the bright- 

 ness of the light ; that is to say, the more intense the light 

 which diffuses itself from the illuminated point in nature, 

 the longer becomes the line w-hich represents it on the 

 picture. Thus, for instance, there proceeds from the sun 

 in the centre of a picture a vertical yellow streak, dividing 

 it into two entirely distinct halves, which are not connected 

 by any horizontal line. In Turner's earlier pictures the 

 disc of the sun is clearly defined, the light equally radiat- 

 ing to all parts ; and even where, through the reflection 

 of water, a vertical streak is produced, there appears, dis- 

 tinctly marked through the vertical streak of light, the line 

 of the horizon, the demarcation of the land in the fore- 

 ground, and the outline of the waves in a horizontal 

 direction. In the pictures, however, of which I am now 

 speaking (the lecturer proceeded to say), the tracing of 

 any detail is perfectly effaced when it falls in the vertical 

 streak of light. Even less illuminated objects, like houses 

 or figures, form considerably elongated streaks of light. 

 In this manner, therefore, houses that stand near the 

 water, or people in a boat, blend so entirely with the 

 reflection in the water, that the horizontal line of demar- 

 cation between house and water or boat and water entirely 

 disappears, and all becomes a conglomeration of vertical 

 lines. Everything that is abnormal in the shape of ob- 

 jects, in the drawing, and even in the colouring of the 

 pictures of this period, can be explained by this vertical 

 diffusion of light. 



How and at what time did this anomaly develop itself? 

 Till the year 1830 all is normal. In 1831 a change in 

 the colouring becomes for the first time perceptible, which 

 gives to the works of Turner a peculiar character not 

 found in any other master. Optically this is caused by 

 an increased intensity of the diffused light proceeding from 

 the most illuminated parts of the landscape. This light 

 forms a haze of a bluish colour which contrasts too much 

 with the surrounding portion in shadow. From the year 

 1833 this diffusion of light becomes more and more verti- 



cal. It gradually increases during the following years. 

 At first it can only be perceived by a careful examination 

 of the picture ; but from the year 1839 the regular vertical 

 streaks become apparent to every one. This increases 

 subsequently to such a degree, that when the pictures are 

 closely examined they appear as if they had been wilfully 

 destroyed by vertical strokes of the brush before they were 

 dry, and it is only from a considerable distance that the 

 object and meaning of the picture can be comprehended. 

 During the last years of Turner's life this peculiarity 

 became so extreme that his pictures can hardly be under- 

 stood at all. 



It is a generally received opinion that Turner adopted 

 a peculiar manner, that he exaggerated it more and more, 

 and that his last works are the result of a deranged intel- 

 lect. I am convinced of the incorrectness, I might almost 

 say of the injustice, of this opinion. According to my 

 idea. Turner's manner is exclusively the result of a change 

 in his tyt-s, which developed itself during the last twenty 

 years of his life. In consequence of it the aspect of nature 

 gradually changed for him, while he continued in an un- 

 conscious, I might almost say in a naive manner, to re- 

 produce what he saw. And he reproduced it so faithfully 

 and accurately, that he enables us distinctly to recognise 

 the nature of the disease of his eyes, to follow its develop- 

 ment step by step, and to prove by an optical contrivance 

 the correctness of our diagnosis. By the aid of this con- 

 trivance we can see nature under the same aspect as he 

 saw and represented it. With the same we can also, as I 

 shall prove to you by an experiment, give to Turnei-'s 

 early pictures the appearance of those of the later period. 



After he had reached the age of fifty-five, the crystalline 

 lenses of Turner's eyes became rather dim, and dispersed 

 the light more strongly, and in consequence threw a bluish 

 mist over illuminated objects. In the years that followed, 

 as often happens in such cases, a clearly defined opacity 

 was formed in the slight and diffuse dimness of the cry- 

 stalline lens. In consequence of this the light was no 

 longer evenly diffused in all directions, but principally 

 dispersed in a vertical direction. At this period the al- 

 teration offers, in the case of a painter, the peculiarity 

 that it only affects the appearance of natural objects, 

 where the light is strong enough to produce this disturbing 

 effect, whilst the light of his painting is too feeble to do 

 so : therefore, the aspect of nature is altered, that of his 

 picture correct. 



The lecturer proceeded to demonstrate the truth of his 

 remarks by a series of experiments, which showed, for 

 instance, a natural tree, and then, by means of lenses pre- 

 pared for the purpose, changed it into a " Turner-tree ; " 

 likewise the artist's early picture of '■ Venice " was shown, 

 and, by means of lenses, changed into the " Venice " of 

 Turner's later period. 



II. — ASTIG.MATISM 



The optical state of the eye during its adaptation for 

 the farthest point, when every effort of accommodation is 

 completely suspended, is called its refraction. 



There are three different kinds of refraction : firstly, 

 that of the normal eye ; secondly, of the short-sighted 

 eye ; thirdly, of the over-sighted eye. 



1. The normal eye, when the activity of its accom- 

 modation is perfectly suspended, is adjusted for the 

 infinite distance ; that is to say, it unites upon the retina 

 parallel rays of light. (Fig. I.) 



2. The short-sighted eye has in consequence of an ex- 

 tension of its axis a stronger refraction, and unites, 

 therefore, in front of the retina the rays of light which 

 proceed from infinite distance. In order to be united 

 upon the retina itself the rays of light must be divergent, 

 that is to say, they must come from a nearer point. The 

 more short- sighted the eye is, the stronger must be the 

 divergency ; such an eye, in order to see distinctly dis- 

 tant objects, must make the rays from a distant object 

 more divergent, by aid of a concave glass. (Fig. 2.) 



