ETC. 293 



The particulars of this case have been given at some length, inas- 

 much as they are regarded by Dr. Bostock 1 and apparently by Dr. 

 Wardrop himself as strikingly confirmatory of those of Cheselden, 

 than which we cannot imagine anything more dissimilar. It will 

 have been noticed, that, from the very first after the reception of 

 sight, she formed an imperfect judgment of objects, and even of dis- 

 tances, although she was devoid of the elements necessary for arriving 

 at an accurate estimate of the latter, the sight of both eyes. This 

 was, doubtless, the chief cause of that groping for objects described by 

 Dr. Wardrop. Of forms, too, she must have had at least an imperfect 

 notion, for we find, that on the thirteenth day after the operation, she 

 stepped from the elevated foot-pavement to the street, " like a person 

 accustomed to the use of her eyes." 



The case is, we think, greatly in favour of the view, that the sight 

 does not require much education to judge with tolerable accuracy of 

 the position, magnitude, distance, surface, and motion of bodies; and 

 that, by a combination of the methods already pointed out, or of some 

 of them, this imperfect knowledge is obtained without the aid of any 

 of the other senses; but is of course acquired more easily and accu- 

 rately with their assistance, especially with that of touch. What other 

 than visual impressions could have communicated to the mind of Miss 

 Biffin whose case was referred to under another head the accurate 

 and minute information she possessed regarding the bodies surrounding 

 her at all distances? Or how does the animal, immediately after birth, 

 acquire its knowledge of distance ? We observe the young of certain 

 animals, immediately after they are extruded from the uterus, turn 

 round and embrace the maternal teat; whilst others, as the partridge, 

 follow the mother in a short time after they have burst the shell. The 

 experience required for obtaining an imperfect knowledge of distance, 

 shape, &c., must, therefore, be trifling; although an accurate acquaint- 

 ance may demand numerous and careful comparisons. This first degree 

 of knowledge is probably obtained, by comparing the visual angle with 

 the intensity of light, shade, and colour, the more accurate appre- 

 ciation following the use of the other methods already described. That 

 the convergence of the axes requires education is demonstrated by the 

 case of the infant. It has been remarked, that the eyeballs harmonize 

 instinctively in their parallel motions ; but the convergence requires an 

 effort of volition, and it is some time before it can be effected, which is 

 probably the great cause of the mal-appreciation of near distances, that 

 we notice in the infant; whilst it seems to exhibit its capability of 

 judging more correctly of objects, that are somewhat more remote; 

 and where less convergence, and consequently less muscular effort, is 

 necessary. 



The numerous optical illusions, which we have been compelled to 

 describe in the progress of the preceding remarks, will render it neces- 

 sary to refer to but few under this head. It has already been said, 

 that we lay it down as a rule, that the progress of light to the eye is 



1 Physiology, 3d edit., p. 703, Lond., 1836. See, also, the case of a gentleman born blind, 

 and successfully operated upon in the eighteenth year of his age, by Dr. J. C. Franz, in 

 Proceedings of the Royal Society, 1840-41, No. 46. 



