22 AMES, PROCTOK AND AMES. 



diffused. Being nearer the primary than the secondary field for red, 

 the vertical lines are sharper than the horizontal ones. The chro- 

 matic edges that exist from the combined figures can be visualized by 

 the amount the different colored edges extend in the different direc- 

 tions. It is regretted again that these figures cannot be reproduced in 

 color which shows the effects much more clearly. The marked differ- 

 ence in characteristic edges in this figure compared with Figure 28 is 

 however plainly evident. 



Figure 29 was taken with the corrected lens of the crosses placed at 

 B, Figure 23. A photograph of the crosses placed at D is so similar 

 that it is not shown. 



Figures 26 and 27 were taken with a lens having approximately the 

 same chromatic and astigmatic aberrations as the eye of the crosses 

 placed at B and D, Figure 23. The characteristic diffusion and 

 accentuation of vertical and horizontal lines for the different colors is 

 evident and a little study will show that it takes place in conformity 

 with the position of the primary and secondary object astigmatic fields 

 for the different colors. 



The marked difference in characteristic imaging between these fig- 

 ures and Figure 29 should be noted. 



In all these photographs the objects were at an angular obliquity of 

 between eighteen and twenty degrees. If the angular obliquity had 

 been less the characteristic imaging would be different due to the 

 difference in the relative positions of the primary and secondary astig- 

 matic object fields for the different colors. 



SUMMARY. 



The foregoing demonstrates that the retinal image of an object in 

 space has characteristics both as to shape and colored edges due to the 

 object's particular position in space relative to the observer and his 

 fixation point. In other words with a given fixation the image of a 

 particular object in the field of view has characteristics which are 

 pecidiar to the image of an object at its particular angular obliquity 

 and distance. 



That these characteristics are of sufficient magnitude to be recog- 

 nized is evidenced by the fact that those doing research in this line 

 have been able to discover and measure them. The accentuation of 

 radial and tangential lines is observable in landscape views. This 

 accentuation can be observed in Figure 30. Hold up the page so that 

 vou can either look by its edge at some distant object or at the small 



