be . TO Pog 
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322 W. ® Rogers on Binocular Vision. # 
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are firmly fastened in a vertical position and parallel to one an- — 
other, at an interval of 7 inches in a rectangular base of wood. 
The object used as a physical line isa thin uniform black cord 
: 
It is needless to detail the various appearances of CD to the — 
reoscope presents us the binocular synthesis of a perspective line 
