26 AMES, PROCTOR AND AMES. 



In paintings made by Mrs. Oakes Ames in which objects on the sides 

 of the pictures were depicted with these characteristics a marked sense 

 of depth is given by the objects taking their proper relative distances. 

 The accentuating of tangential and radial lines in their proper planes 

 is found in many paintings, especially those of Turner in whose work it 

 is apparent in the accentuation of tangential lines inside the focus and 

 of radial lines on and behind the object plane of the scene he is painting. 

 The accentuating of tangential lines in the foreground is found in many 

 works of art and might be called almost a trick of composition to pro- 

 duce an effect of depth. 



Although a large part of the above described effects are due to color 

 and therefore cannot be reproduced in black and white, the photo- 

 graphs in Figures 31 a and b taken with a lens having approximately 

 the same oblique aberrations as the eye, and 32 a and b taken with a 

 corrected lens, are shown to give an idea of the general differences 

 obtained. The photographs in Figure 31 a and b are believed to give a 

 greater effect of depth and to be generally more pleasing than those 

 in Figure 32 a and b. 9 



The accentuation of the tangential lines and softening of the radial 

 lines in the foreground are very apparent in the candle stick in Figure 

 31a. The accentuation of the radial lines and the softening of the 

 tangential lines in the background and plane of the focus are apparent 

 in the books in Figure 31a and in the objects on the right and left of 

 Figure 31b. 



The difference in the size of the books in Figures 31a and 32a is 

 due to the distortion in Figure 31a. This distortion is approximately 

 the same as exists in the eye. This difference in size may help to cause 

 Figure 31a to give a greater sense of depth than Figure 32a. 



Chapter IV. 

 DISTORTION. 



There is still another factor that affects the nature of the images of 

 an object situated on one side of our line of vision. That is distortion. 

 It can be defined as that characteristic of a lens which causes variation 

 in distance between points in the image field which in the object field 

 are equidistant. The eye is subject to so-called barrel distortion, 



9 It is regretted that the general loss of detail due to reproduction masks 

 much of the effect which is apparent in the original photographs. 



