184 O.N. Rood on the Perception of Distance and Color. 
Art. XXI.—On the Relation between our Perception of Distance 
: and Color ; by Prof. O. N. Roop. 
THE fact that a landscape appears more vivid in color, when 
viewed by the eyes brought into an abnormal position, as in 
looking under the arm, &c., is well known. 
Some persons have attempted to explain this fact by the influ- 
ence of an augmented pressure of the blood upon the retina. 
In an easy reclining posture, where such pressure can hardly 
exist, I observe this heightening of tints with great distinctness, 
also by viewing the inverted image of the landscape by total 
reflexion through a rectangular prism, the head being in its 
natural position. 
Dr. A. Miiller* with more probability has referred this appear- — 
ance to the different accommodation of the eye for horizontal and 
vertical lines. 
exception of objects in the foreground, all things seem to lie not 
far removed from the same vertical plane. 
The reason is partly to be found in the fact, that while in nor- 
mal vision our binocular perception of depth is obtained by 
regarding vertical lines, trees, &c., in vertical vision the same 
objects, though instinctively sought afford us no information. 
~ (2.) In normal vision with a single eye, there is certainly, in a 
binocular sense no perception of depth, nevertheless the mind 
occupies itself with the idea of distance, and if the objects are 
familiar there is no augmentation of color perceived. By invert- 
ing the image of the landscape with a rectangular prism the 
objeets fall into almost one plane, are diminished in apparent 
magnitude, and the mind as to trace distances through this 
maze, is forced to dwell on the mass of tints presented. 
* Pogg., vol. Ixxxvi, p. 147. 
