-J. LeConte—Phenomena of Binocular Vision. 87 
Experiment 4.—For this purpose I prepare a plane a yard 
square, and cover it with vertical and horizontal lines. In 
by projection 
xperiment 5.—Determined to neglect no means of testing 
the correctness of these results, I next made experiments in the 
open air, using the sky as the plane upon which to cast the 
image. ‘This spatial concave is of course everywhere perpen- 
dicular to the line of sight, and therefore eliminates eve 
source of error from projection. Standing with head erect, I 
gaze on a perpendicular flag-staff until a strong impression is 
made on the retina. If now holding the head steady, I cast 
the image on the sky obliquely upward and to the right, the 
image inclines decidedly to the right; if thrown similarly to 
. 
