Chemistry Reference
In-Depth Information
Figure 1.1
M.C. Escher's 'Fish, Vignette' Copyright 2008 The M.C. Escher Company-
Holland. All rights reserved. www.mcescher.com.
Figure 1.2 shows the ceiling of the Arab Room of Cardiff Castle. It is clear that the dec-
orators have gone to a lot of trouble to use symmetry. In this case, a rotation of the image
through 90
◦
would interchange the positions of the windows; but, since they are identical,
the pattern would appear unchanged. Four such rotations are possible, with the last return-
ing each part of the ceiling to exactly its initial location. This image also has additional
symmetry properties not possessed by Escher's fish. Imagine a line drawn horizontally
across the image so that it passes through the centre of the left- and right-hand windows.
The two sections of the image are now reflections of each other, with each feature in the
upper part of the picture repeated in the lower half, as if reflected in a mirror standing
