88 W. B. Rogers on Binocular Vision. 
the right pin as visible to the left eye; and on the left of it, that 
of the left pin as seen by the right eye ; and, provided the eyes 
be steadily fixed on the resultant, these lateral images appear 
lie at the same distance and to have the same magnitude as the 
resultant. 
The following emg of this experiment is easily repeated, 
and illustrates the same law of binocular combination in a very 
simple and kahit manner. Omitting the remote pin and fixing 
the two others about 18 inches from the near end of the iy = bs 
through the g R 
situated in the rye oft 
ther in the same direction, a appear within the apartment 
between him and the glass ro at oid changes he cal 
not fail to notice that it ieee a consts Ay distance, from the 
eyes, and has for its position the point of me e of the optic — 
axes. 
This éffect is even more striking when the bright surface 
front is that of a globular astral lamp. In this case by com 
mencing the observation at a distance of 12 or 15 feet from the 
lamp we see the binocular image on the near side of this object, 
but as we slowly approach we ‘observe the image apparently a 
etrating the luminous globe, and at a less distance still we see i 
beyond the lamp as if we were looking through the glass at areal 
object in that position. 
In the preceding eases the resultant is formed by con verging 
the optic axes to a point more remote than the two objects to be 
united, but it is easy, by a different arrangement of the pins, 10 
prove that the same law holds for the position of the binoculat 
2. 
