232											8
                                                                      
                                                                      	a. in their centres, would be easily supported by the
                                                                      shorter span of lintol in a, (and similarly, weights of
                                                                      masonry which would break the sloping stones in b. would
                                                                      be readily sustained by b,) and the second, that supposing
                                                                      the pillars in a, built of small stones - or even of a
                                                                      soft single stone, the weight of the separate lintols
                                                                      would have a tendency to cause fissures in the direction
                                                                      f f while the stone introduced in a, equalizes their
                                                                      pressure over the whole top of the pillar.
                                                                      (x)   This arrangement is the best possible.  It may
                                                                      indeed be asked why the process should not be continued,
                                                                      as in a4.  but in this case the superstructure is evi-
                                                                      dently so much raised that it would have been better to
                                                                      have made the shafts of the pillars longer at once;
                                                                      better  because simpler and requiring less material:
                                                                      on the other hand it may be asked, why not dispense
                                                                       with the upper flat headstone and employ only the
                                                                      expanding stone beneath;  as a5 (opposite) but, though this
                                                                      arrangement is admissible in the case of the single
                                                                      lintol or close set arch, a, d, it is evidently weak and
                                                                      unsafe when the masonry is smaller and bears on the edge
                                                                      of the headstone as in the cases a2 d2 which would become
                                                                      a6 d6 both of them evidently unsafe forms if the weight of
                                                                      the superstructure should happen

[Version 0.05: May 2008]