J. LeConte— Phenomena of Binocular Vision. 83 
Art. X.—On some Phenomena of Binocular Vision ; by 
JOSEPH LECONTE. 
[Read before the National Academy of Sciences, April 20, 1880.] 
XI—Laws of Ocular Motion.* 
Ix March, 1869, I published a paper “on the rotation of the 
eyes on their optic axes, in convergence.’ The results reached 
in that paper were briefly as follows: : 
1. In optic convergence in the primary visual plane there is 
a rotation of both eyes on their optic axes outward, and this 
rotation increases with the degree of convergence. 
2. In inclining the visual plane downward the rotation for 
the same degree of cofivergence decreases until when the inclin- 
ation is 45° below the primary position, the rotation becomes 
zero for all degrees of convergence. Below 45° the rotation 
ecomes inward. 
3. In elevating the visual plane the rotation, for strong con- 
vergence, zncreases. 
convergence. 
t was in this spirit and the expectation of this result, that I 
' recently undertook a re-investigation of the whole subject of 
the laws of ocular motion. My first effort was directed to a 
thorough mastering of the law of Listing; for the statements 
* For the other rs on thi j is J II, vol. xlvii, pp. 68 
and 153, III, vol. aes paki, bois Goria Rit: nell wok ah p. 159. er 
