J. LeVonte on Binocular Vision. 157 
black lines, both vertical and horizontal, crossing one another 
at small angle, as if the images of both eyes had rotated on 
6. 
y, 
soe 
a, 
the visual line in opposite directions, This angle of crossing 
increases as the plane of the diagram is brought nearer and 
W 
that the white lines belong to the right eye and the black lines 
to the left eye, we can therefore determine the direction in 
Which each image rotates. I find always that the black lines 
or the image of the left eye rotates to the right #” \ and the 
White lines or the image of the right eye rotates to the lett 
. Now as the image always moves in a direction con- 
trary to the motion of the eye (differing in this respect from 
ae: this indicates a rotation of both eyes un the optic axes 
outward ; : 
To test this question still farther I constructed another dia- 
gtam with the horizontal lines continuous across but the roe 
cals not perfectly vertical, the upper ends of those of the right 
half inclining to the Jeft and those of the left half to the right 
