roman ogee geometry

Sun, Dec 28, 2003, 3:56pm (EST-3) [email protected] (hex)
queries:
Hi all,
Maybe I'm dense and everybody else on the planet already knows the
answer to the following question.
Is it by definition that a roman ogee is self-complementary? =A0 I don't
think that is true for all ogee's. <snip>

I thought the correct spelling was "orgy".

LMAO

JOAT
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Andy Dingley <[email protected]> wrote in message news:<[email protected]>...
> On 28 Dec 2003 15:56:38 -0800, [email protected] (hex)
> wrote:
>
> >Is it by definition that a roman ogee is self-complementary? I don't
> >think that is true for all ogee's. Yes/no?
>
> Yes (I'm pretty sure) and definitely no.
>

<Much information snipped>

Andy,
Thanks for the encyclical reply including references! -- much more
interesting than the feeble attempt to drive the discussion far off
topic and into the gutter. I didn't see your reply go by and had
given up the thread as dead/useless.

hex
-30-

On 28 Dec 2003 15:56:38 -0800, [email protected] (hex)
wrote:

>Is it by definition that a roman ogee is self-complementary? I don't
>think that is true for all ogee's. Yes/no?

Yes (I'm pretty sure) and definitely no.

An ogee is a moulding derived a cyma curve. Architectural and
archaeological references may talk about cyma more than ogee. The cyma
has an ancient historical tradition and they were widely used by both
Greeks and Romans as the basis for an architectural frieze or cornice,
then carved with a moulding; acanthus leaves, egg & dart etc..

As is widely known, you can cut a cyma either way up - cyma recta, or
cyma reversa. The cyma recta (concave part above convex) on a cornice
is more usual on the cymatium - the very top moulding, with nothing
above it. Lower down in the architrave and often used to support the
cornice, the cyma reversa has the convex part (the bulge) above the
concave. This is thought of as visually more "supporting" than the
cyma recta which looks "hollow" and "fragile" on its upper edge.

The ogee (strictly speaking) is a cyma reversa. When used in a
freehand router on a table top, the typical "ogee" router cutter
actually cuts the other sort, the cyma recta. Although this cutter in
a table can cut either way, depending on how you feed the stock.

The Greek and Roman cyma curves are distinguished by the Greek being
based on ellipses, the Roman on circular arcs. It's common for the
Greek cyma to be asymmetric, usually a cyma recta with a smaller lower
curve to give a larger area for a carved hollow moulding. As far as my
refs can tell though, all the Roman cyma are symmetrical.


A good text on these styles is
Carving Architectural Detail in Wood
Frederick Wilbur
<http://www.amazon.com/exec/obidos/tg/detail/-/1861081588/codesmiths-20>

It's a book of two parts. One is obviously a guide to the technical
aspects of carving such details. Perhaps the more interesting though
is a very accessible history of architectural details in the classic
tradition of Greece, Rome and Palladio, through to Colonial America.
It does assume a certain level of carving skill and is thankfully
brief on the usual repetition of basic techniques. Any woodworker (or
even a stonemason) looking to choose the mouldings to use on 18th
century furniture, interiors fittings such as mantelpieces, or an
exterior facade or portico will find this a very useful book.


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