With very rare exceptions, as in the southwest spire of
Chartres Cathedral, this form was always used. Now it will be seen that
a difficulty arises in the beginning, how to unite the octagon of the
spire with the square of the tower. There are four triangular spaces at
the summit of the tower left uncovered by the superstructure; and how
best to treat these, simple as the task may seem, constitutes what may
be called the touchstone of architectural genius in spire-building.
There are several general ways of effecting this, each of them subject
to such modifications, in individual instances, as to give them an
ever-varying character.
Perhaps the earliest method was simply to occupy those triangular spaces
with pyramidal masses of masonry, sloping back against the adjacent
faces of the tower,--an expedient which Nature herself might have
suggested in the first snow-storm. Then they boldly cut the Gordian knot
by shaving off the corners of the tower at the top, thus creating there
an octagonal platform, to which the spire would exactly correspond.
Still oftener they chamfered the spire upwards from the corners of the
tower: in other words, they placed, as it were, a square spire on
their tower, occupying the whole of its summit, and then obtained the
necessary octangularity by shaving off the angles of the spire from the
apex to a certain point near the base, where the cutting was continued
obliquely to the corners of the tower.
Pages:
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245