£88 Prof. W. B. Rogers on Binocular Vision. 
in binocular vision, are believed to be in part new, and are in part 
modified repetitions of experiments already described by Profs. 
Wheatstone and Dove. They offer what seems to be decisive 
and then directing the eyes towards the opposite wall of the 
apartment, a single spectrum will be observed having the attitude 
and relief of the original binocular resultant. ; 
As a strong illumination of the lines is necessary to bring out 
the most striking effect, the card-board should be held between 
the eyes and some brilliantly white surface, as the globe of a 
solar lamp or a strongly illuminated cloud, care being taken to 
prevent the entrance of extraneous light. , 
3. Using the same arrangement, let the luminous lines be 
regarded in succession each by the corresponding eye, the other 
eye being shaded so that no direct binocular combination can be 
formed. On looking toward the wall it will be seen that the two 
subjective images unite to form a single spectral line having the same 
relief as if the lines had been directly combined with or without the 
stereoscope. a 
While the perspective image continues distinctly visible, let 
either eye be closed the other being still directed towar the 
Ww i : 
to the subjective image in the eye which has remained . 
When the subjective impressions have been sufficiently strong ! 
18 easy to alternate these effects by projecting. first the picture 
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