[Illustration]
In our last example we have a succession of keys built up by
interlocking the wards and bows one within the other, upon the summit of
which may, by special care, be balanced a bottle or similar object.
Where the bottle is added to the pile, it takes the place of the
uppermost key shown in our illustration, and rests upon one taking a
more gentle incline, as in the case of the one immediately below. This
rather ambitious structure forms a fitting climax to our series, and may
be left to the ingenuity of the reader, whose accumulated experience
should by this time be good equipment for the negotiation of the
difficulties to be surmounted.
_Miss Cairn's Cough-Drops._