201 Mr. S. Rowley on a New Theory of Vision. 



of the object at A will be a habit whereby, when the axes are 

 directed to the images of the object at B, the mind will be led 

 to mistake 2 T 1 ^ inches (the distance in the surface of the left 

 eye's image at a 1 of the object at A to the right of its image at 

 B of the object at B) for T 8 inch, and 18 inches (the distance 

 of the surface of vision from the base) for 6 inches ; and 2 T \ 

 inches (the distance of the surface of the right eye's image at a 

 of the object at A to the left of its image at B of the object at 

 B) for f\ T inch, and 18 inches (the distance of the surface of 

 vision from the base) for 6 inches. 



Thus, since the more remote parts of a solid object will seem 

 to be seen at equally more remote distances in the image, and 

 the entire image at a distance equal to that of the object, the 

 image will seem to be seen with the same form and magnitude 

 as really pertain to the object*. 



We are now also prepared to explain the cases in which the 

 visible image, though the object be situated at a greater or less 

 distance from the base of vision than the point of convergence 

 of the axes, is accepted by consciousness in its true place, as in 

 the experiments with the equidistant pins, with the wafers upon 

 glass, and the figures on the papered wall. 



In these cases it will be perceived that any two images seen 

 as one, though proceeding from two different objects, have the 

 same positions in the surfaces of vision as they would if they 

 proceeded from a single object placed at the intersection of 

 the lines drawn from the two different objects to the eyes. 

 Further, so great is the propensity to appreciate singly, that 

 any slight discrepancy between these images and those produced 

 by one and the same object will not prevent an acceptance of a 

 correspondence; and since all the equivalent single objects would 

 lie at the same distance, no habit can exist to influence the mind 

 with respect to any images to locate the surfaces of vision at a 

 greater or less distance from the base of vision than the true, 

 llence all the images will be apprehended in their true visible 

 places. But if the interval between any two objects of such a 

 series should differ from the other intervals, then for the two (of 

 the four images presented) which are accepted as corresponding, 

 or capable of being seen singly in direct vision, if these should 

 be lateral (or if central, then for all the rest), from the necessary 

 principle of habit above laid down, the surfaces of vision, mea- 

 sured from the common centre, will seem, to exist at such a dis- 



* In ordinary lateral vision (i. e. vision had at the sides of the line of in- 

 tersection of the surfaces of vision) two corresponding images, or the cor- 

 responding parts of two complex images, at the concurrence of the axes 

 are appreciated singly by reason of inattention to, or neglect of, one of 

 them. 



