RO a Cos ee aan 
W. B. Rogers on Binocular Vision. 181 
ters of the size and form of fig. 82. 
tious of a more partial kind require a special effort. Substituting 
the letters D... V of the same size as in fig. 82 equally striking 
effects of partial combination may be observed. 
In these experiments the observer cannot fail to notice the oc- 
casional invisibility of parts of lines when very near to others 
analysis of the phenomena, I am satisfied that most of the 
changes which present themselves in such cases, including the 
apparent breaking up and reunion of parts of letters mentioned 
by Prof. Wheatstone, are really due to imperfect and shifting 
as in all other attempts at uniting complex and very dissim- 
ilar Pictures, arise in a large degree from alternating combina- 
tions between parts capable of binocular union and cannot be 
ascribed except very partially to the actual vanishing and re-ap- 
Pearing of the components. : y 
Seconn.— Of the binocular union of figures differing both in 
height and breadth. 
®: apparent coincidence where the figures are unequal in both 
dimensions, Se 
31. Phenomena of vertical binocular adjustment. 
tn referring to the binocular combination of vertieal lines 
slightly differing in height, and whose lower ends are placed on _ 
the same horizontal level, it was remarked (6) that a slight turn- 
