170 J. LeConte on Binocular Vision. 
double at B’, the images being crossed, and approach one 
another and meet at QO, in other words, will appear thus: |” | 
while BW will also double at B but not cross (i. e., each ‘| | 
image will have the same name as the eye), and will be 
Lastly, if the ver- 
i 
seen to converge and meet at W thus 
cross one another like 
Meissner accounts for these phenomena by supposing that, in 
converging the optic axis, the eyes rotate on the optic axis out- 
ward so that the vertical lines of demarkation CD no longer 
coincide perfect!y with the vertical meridians AB (fig. 12,) as 
they do when the eyes are 
in + rimary direction 
(the axis parallel) but cross 
tical line pass through the point of sight A, the images will | 
ike an X. ; 
12,) which therefore no longer coincides wi 
clination to the visual plane, as the convergence of the 
os ie 
creases. 3. That in turning the visual plane downward, 
