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The Distorting Mirror


Opticians sometimes grind a glass mirror concave in one direction

only, or longitudinally; it is in fact a concave portion of a

cylinder, the breadth of which may be considered that of the mirror. A

person looking at his face in this mirror, in the direction of its

concavity, will see it curiously distorted in a very lengthened

appearance; and by turning the cylindrical mirror a quarter round, his

visage will appear distorted another way, by an apparent increase in

width only. If in a very near situation before it, you put your finger

on the right hand side of your nose, it will appear the same in the

mirror; but if in a distant situation, somewhat beyond the centre of

concavity, you again look at your face in the mirror, your finger will

appear to be removed to the other side of your nose.



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