ART AND EYESIGHT. 



4 6 3 



0'83 of a dioptre, and for this experiment I have chosen one of 

 the lenses which is very nearly the same strength. Of course, the 

 effect is magnified, as the camera is larger than the eye. But the 

 eye can recognize differences infinitely more minute than those 

 which it is possible to reproduce here, and the physiological dis- 

 tortion is even greater than that which it is possible to represent 

 on the printed page. A picture taken with such a combination 

 of lenses is shown in Fig. 2. In this it will be noticed that while 

 the vertical lines are all clearly marked the horizontal ones are 

 blurred and indistinct. If, now, for any reason the globe of the 

 eye has the same distortion from side to side instead of from 

 above downward, this can be imitated by placing the cylindrical 

 lens before our camera with the axis vertical instead of horizon- 

 tal. The result is shown in Fig. 3. The effect in this case is to 

 blur the lines which before were clear, and make clear those 

 which were blurred. For example, the horizontal line extending 



Fig. 2. 



along the top of the wall of the terrace, and even some of the 

 strata of the stones, can be distinguished, and the horizontal lines 

 in the building itself are also well defined. On the contrary, the 

 vertical lines are blurred. The pillars at the top of the tower and 

 on the dome itself are all indistinct, while, as a whole, the build- 



