T. W. Backhouse—Physiological Optics. 809 
is also moved till it is apparently placed exactly in the plane of 
the phantom, I have found that it is then exactly i 
id. th ctly parallel with 
the real wall. At least, in eight independent observations and 
eG 3 have not access to Rogers’s paper on the combination of © 
_ Points differing in latitude, but 1 apprehend this can be effec- 
a ted only by moving the optic axis of one eye higher up than — 
that of the other, so that the images of the two points still fall — 
the rresponding points of the retina. As I have just shown, — 
_ Se experiment here described does not bear on the subject, — 
<a and therefore cannot in the least invalidate the theory of cor- — 
| Peponding points. ee ee 
___, Vol. xxiii, p. 357.—I have seen stereographs of the moon — 
abt that the one he alludes to 
a pray. + do nok dispute Stevene® = 
og Re ee pes 3 greg sir epee 
t of relief; but these statements about: 
and moon, if not explained, are calcu- 
