Iron ones. </s> <s>If Lead is daubed with any Sort <lb/>
of Filch, it quickly &longs;poils; and for this Rea&longs;on <lb/>
we &longs;hould take Care that our Roof be not a <lb/>
convenient Harbour for Birds; or if it is a like<lb/>
ly Place for them to get together in, we &longs;hould <lb/>
make our Stuff thick where their Dung is to <lb/>
fall. <emph type="italics"/>Eu&longs;ebius<emph.end type="italics"/> tells us, that all round the Top <lb/>
of <emph type="italics"/>Solomon<emph.end type="italics"/>'s Temple there was a great Number <lb/>
of Chains, to which hung four hundred little <lb/>
Bells continually vibrating, the Noi&longs;e of which <lb/>
drove away the Birds. </s> <s>In the Covering we <lb/>
al&longs;o adorn the Ridge, Gutters and Angles, by <lb/>
&longs;etting up Va&longs;es, Balls, Statues, Chariots and <lb/>
the like, each of which we &longs;hall &longs;peak of in <lb/>
particular in its due Place. </s> <s>At pre&longs;ent I do <lb/>
not call to Mind any thing further relating to <lb/>
this Sort of Ornaments in general, except that <lb/>
each be adapted to the Place to which it is <lb/>
mo&longs;t &longs;uitable.</s>

 <s>CHAP. XII.</s>

 <s><emph type="italics"/>That the Ornaments of the Apertures are very plea&longs;ing, but are attended with <lb/>
many and various Difficulties and Inconveniences; that the fal&longs;e Apertures <lb/>
are of two Sorts, and what is required in each.<emph.end type="italics"/></s>

 <s>The Ornaments of the Aperture give no <lb/>
&longs;mall Beauty and Dignity to the Work, <lb/>
but they are attended with many great Diffi<lb/>
culties, which cannot be provided again&longs;t <lb/>
without a good deal of Skill in the Artificer, <lb/>
and a con&longs;iderable Expence. </s> <s>They require very <lb/>
large Stones, &longs;ound, equal, hand&longs;ome and rare, <lb/>
which are Things not ea&longs;ily to be got, and <lb/>
when got not ea&longs;ily removed, poli&longs;hed, or &longs;et <lb/>
up according to your Intention. <emph type="italics"/>Cicero<emph.end type="italics"/> &longs;ays, <lb/>
that the Architects owned they could not &longs;et <lb/>
up a Column exactly perpendicular, which in <lb/>
all Apertures is ab&longs;olutely nece&longs;&longs;ary both with <lb/>
Re&longs;pect to Duration and Beauty. </s> <s>There are <lb/>
other Inconveniencies be&longs;ides; which, as far as <lb/>
lies in our Power, we &longs;hall endeavour to pro<lb/>
vide again&longs;t. </s> <s>An Aperture naturally implies <lb/>
an Opening; but &longs;ometimes behind this Open<lb/>
ing we run up a Wall which makes a Kind <lb/>
of fal&longs;e Opening which is not pervious but <lb/>
clo&longs;ed up; which for this Rea&longs;on we &longs;hall ac<lb/>
cordingly call a fal&longs;e Aperture. </s> <s>This Sort of <lb/>
Ornaments, as indeed were mo&longs;t of tho&longs;e <lb/>
which &longs;erve either to &longs;trengthen the Work or <lb/>
to &longs;ave Expence, was fir&longs;t invented by the <lb/>
Carpenters, and afterwards imitated by the <lb/>
Ma&longs;ons, who thereby gave no &longs;mall Beauty to <lb/>
their Structures. </s> <s>Any of the&longs;e Apertures would <lb/>
be more beautiful if their Ribs were all of one <lb/>
Piece, made of one entire Stone; and next to <lb/>
this, is the having the Parts &longs;o nicely joined <lb/>
that the Joints cannot be &longs;een. </s> <s>The Ancients <lb/>
u&longs;ed to erect their Columns and other Stones <lb/>
which &longs;erved as Ribs to the&longs;e fal&longs;e Apertures, <lb/>
and fix them firm on their Ba&longs;es, before they <lb/>
carried up the Wall; and herein they did very <lb/>
wi&longs;ely; for by this Means they had more Room <lb/>
to u&longs;e their Engines, and could take the Per<lb/>
pendicular more exactly. </s> <s>You may plant your <lb/>
Column perpendicular upon its Ba&longs;e in the fol<lb/>
lowing Manner: In the Ba&longs;e and at the Top <lb/>
and Bottom of the Column mark the exact <lb/>
Center of each Circle. </s> <s>Into the Center of the <lb/>
Ba&longs;e fa&longs;ten an iron Pin, &longs;oddering it in with <lb/>
Lead, and make a Hole in the Center of the <lb/>
Bottom of the Column, ju&longs;t big enough to re<lb/>
ceive the Pin which &longs;ticks up in the Center of <lb/>
the Ba&longs;e. </s> <s>In the Top of your Engine, or <lb/>
Scaffolding, make a Mark exactly perpendicu<lb/>
lar over the Pin which &longs;ticks up in the Center <lb/>
of the Ba&longs;e, which you may find by letting &longs;all <lb/>
Line from thence to that Pin. </s> <s>When you <lb/>
have thus prepared every Thing, it will be no <lb/>
hard Matter to move the Head of the Shaft <lb/>
till its Center an&longs;wers exactly to the Mark <lb/>
which you have made above and is perpendi<lb/>
cular to the Center of its Ba&longs;e. </s> <s>I have ob&longs;erv<lb/>
ed from the Works of the Ancients that the <lb/>
&longs;ofter Sort of Marble may be &longs;moothed with <lb/>
the very &longs;ame In&longs;truments with which we <lb/>
plane Wood. </s> <s>The Ancients al&longs;o u&longs;ed to &longs;et <lb/>
up their Stones quite rough, only &longs;moothing <lb/>
the Heads and Sides of them which were to <lb/>
join to other Stones, and a&longs;terwards when the <lb/>
Building was rai&longs;ed, they poli&longs;hed the Faces of <lb/>
the Stones, which they had le&longs;t rough before; <lb/>
and this I believe they did that they might <lb/>
leave the lea&longs;t Expence that was po&longs;&longs;ible to the <lb/>
Hazards of their Engines: For it would have <lb/>
been a much greater Lo&longs;s to them, if by Acci<lb/>
dent any Stone that was quite &longs;moothed and <lb/>
poli&longs;hed had been let fall and broke, than if