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apparent direction of eyes in a portrait. 
pally by the nose and other parts of it that are most promi- 
nent, because these, in nature, are subject to the greatest 
changes of perspective form by any alteration of position ; 
and we scarcely notice those smaller variations of figure, to 
which even parts least prominent are liable when seen very 
obliquely. 
It must be obvious to the most superficial observer, that 
the same perspective form which correctly represents a cer- 
tain pair of eyes in one position of the face, cannot be an 
exact representation of the same eyes in another ; but in 
cases of such slight obliquity as is usually given to the eyes 
in a portrait that is intended to look at the spectator, the 
variation of the form of the lids from obliquity is less than 
the difference observable in the eyes of different persons. 
Hence it is that a pair of eyes drawn looking at us, will 
best admit of being warped from their intended direction 
by application of a new position of the other features of the 
face. 
The converse of this experiment may also be made with 
success within the same limited extent. Eyes drawn origi- 
nally looking a little to one side of us, may be made to look 
at us by applying other features in a suitable position. But 
although a change of twenty or perhaps thirty degrees may 
be effected, it is not to be supposed that a turn of ninety de- 
grees can be produced. It would be absurd to imagine that 
an eye drawn in profile could be made to look full upon us, 
or that an eye looking nearly at us could be made to appear 
in profile. 
If an attempt be made to carry the experiment beyond 
reasonable limits, so that the perspective form of the eyes is 
