241											15
                                                                      
                                                                      	diameters shall be of due proportion ao the roof weight
                                                                      The su[w]ccessive floors are nothing but so many ties upon
                                                                      the shaft, which  may be theoretically considered as
                                                                      continuous and bound by the intermediate floor in order to
                                                                      prevent its bending:  Evidently however it is more secure
	Note:  The superimposition of shafts with level architraves          and more graceful to construct the elevation of successive
  a style not en[b]ough worked at, except in round end of             shafts, with the floors laid upon them by means of true
 Pisa and baptistery of Parma.                                        capitals than of one continuous shaft with the floor let
                                                                      in it.
                                                                      When a shaft is detached, its strength and best form is
                                                                      one tapering slightly to the top;  and swelling as it des-
                                                                      cends:  but when it is tall and supported by a wall,
                                                                      such a form would be inconvenient, and indeed in very
                                                                      narrow shafts impreceptible:  Such shafts are true
                                                                      verticals therefore and of constant sections.
                                                                      When a roof is raised high upon continuous shaftsm the
                                                                      wall veil between them has the function of a buttress;
                                                                      and their justproportion is that which appears adequate
                                                                      to the support of the roof at an ordinary height; and which
                                                                      only requires the aid of the walls to prevent its greant
                                                                      l ngth from bending;  the External buttress have
                                                                       exactly the same function;  and each pier of such a
                                                                      building may be considered as supported by wall buttresses
                                                                      on thr[e]e[m]e of its four sides.

[Version 0.05: May 2008]