Journal . ither becausethey affect the observation only in an uncertain manner or that themind jails to judge of them. This is the phenomenon of simultaneous contrast commontoall perceptions of the senses. A man of middle height appearssmall beside a tall man, because at the moment it is impressedon us that there are taller men than he, and we lose sight of thefact that there are smaller. The same man of middle heightappears tall beside a man of small stature. 4. The appearance oj objects is influenced by adjacent obliquelines. We perceive more distinctly the difference of directionpresented a
Journal . ither becausethey affect the observation only in an uncertain manner or that themind jails to judge of them. This is the phenomenon of simultaneous contrast commontoall perceptions of the senses. A man of middle height appearssmall beside a tall man, because at the moment it is impressedon us that there are taller men than he, and we lose sight of thefact that there are smaller. The same man of middle heightappears tall beside a man of small stature. 4. The appearance oj objects is influenced by adjacent obliquelines. We perceive more distinctly the difference of directionpresented at the intersection of two sides of an acute or obtuseangle than the direction that exists between one of the sides andthe perpendicular which we imagine placed on the other side,but which is not marked. The Romans were well acquainted with the influence ofoblique lines. At Pompeii, fresco paintings are to be found inwhich the lines are not parallel, so that they satisfy the eyeinfluenced by adjacent In the above figure a, b, and c, d, which are straight parallellines, appear to bend outwards in the middle, the effect beingcaused by the oblique lines. 5. Brightly lighted surjaces appear larger than they really areand the dark surjaces surrounding them appear diminished. This phenomenon comes under the heading of irradiation,and produces various effects according to the form of the figurelighted. When the light reflected from an object viewed isfaint it can be seen more distinctly at night when we look awayfrom it, which fact seems curious, the law being that an objectis distinctly seen when we gaze upon it. As an illustration itmay be remarked that when we want to see a faint and particularstar it will at once disappear when we gaze at it and the bestway to see it is to look away from it—a little to one side or the 148 RECONNAISSANCE SURVEYS. other. This does not refer only to persons suffering from astig-matism of the eye, who normally look to one side of an objectwhe
Size: 3120px × 801px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade186, bookpublisherlondon, bookyear1861
