2 J. LeConte on Binocular Vision. 
tively distingu shes between homonymous and heteronymous images, 
referring the one to a position beyond, and the other to a position 
on this side the point of sight. 
This last point is so important in the theory of binocular 
rspective, and so at variance with the accepted view on this 
subject that I must dwell upon it a moment. It is now gener- 
ally admitted that Wheatstone’s idea of a complete mental com- 
bination of dissimilar pictures or ot. ws not true, hg in 
stereoscopic experiments or in ral vision ;* but the theory 
thorities on this subject, i siiat puckpeakive is aS ally the 
result of rapid changes of convergence, or what I have called 
ranging of the eyes back and forth from foreground to back- 
round and vice versa. 7 J think, however, close attention to 
jects while Abas steadily at one point, even in those cases in 
perspective. This is accounted for on the principle just an- 
Gonoct ¥ viz: that the eye instinctively distinguishes between 
homonymous and heteronymous images, referring the former to 
objects beyond and the latter to objects on this — _ point e 
aad, or in other words, each eye knows its own 1 
true we are not usually conscious of as kirg distinetion, 
* Mr. Townes in the elaborate paper “on the physiology of vision” already 
alluded to in my last paper, (III, 1, 33 ,) devotes much time and many experiments 
to the subversion of this view, under the impression that it is still the universally 
acce 
+ an admirable review of the wae Dh ates by Claparéde, Bib. Univ. 
~a es Sci. Nouv. Per., vol. iii, p, 138 seq. 
. 155. 
eee I give Wheatstone’s result on the authority of De la Rive, (vol. ii, p. 184, 
trans.) og of Daguin Seok iii, p. Is ——. we is somewhat remarkable that 
nearly e Whe s result as a little less than 
ee Hehe pet lew second. “Prof Mase i Gin seal + admirable 
researches on this ‘ene eahers ‘naforvanately ts fallen into the same mistake. The 
quodoon Of ase but it is the time 
orcupied by the electric current in in passing from oue interruption of the wire to 
