The
English language certainly contains some strange words, often with obscure
etymological origins. Even everyday objects can be difficult to name. I came
across the word ‘ogive’ last year. Not knowing its meaning, I looked it up, and
now see ogives almost everywhere. (The more you know, the more you look and the
more you see.)
An ogive
is defined as the roundly tapered end of an object, be it two- or
three-dimensional. Geometrically, it is formed from two parallel straight lines
and two intersecting arcs whose radii are greater than the distance between the
lines (Figure 48.1).
Figure
48.1: Diagrammatic representation of an ogive. The so-called ‘sharpness’, normally
denoted as ‘E’, of this particular ogive is given by the ratio 120/100, i.e.
1.2. The greater the ratio, the sharper the tapered end.
Copyright
© 2004 Securiger
Arguably the most
common example is the Gothic (or ogival) Arch. Although widely considered to be a
medieval structure, it is, in fact, Islamic. Europe is full of Gothic
architecture, which often defines its most celebrated buildings, particularly
cathedrals and churches.
Andalucía
provides one of the most striking portrayals of this feature. Despite the
Christian Reconquista of the 13th to 15th
century, much of the original Islamic mudéjar style remained popular, and for good reason. Christians built their churches
with ogives large and small, thus tacitly acknowledging the artistry of their
Muslim predecessors. The finest testimony has to be Seville Cathedral – or, to
give it its full title, El Catedral de Santa María de la
Sede. This is the largest Gothic building – and third largest cathedral –
in the world. It took the entire 15th century to construct, and an entire day
for me to explore.
The
cathedral’s ogives are too numerous to count, although its stained-glass windows
and 15 exterior doors would be the best places to begin (Figure 48.2). Aesthetically,
the ogive is a masterstroke; but that is, I admit, purely subjective. What
would be impossible to deny, however, is one of its most important functional
attributes: the ability to resist the enormous gravitational force of the wall
above it. (Perhaps this indicates to us the origin of the word: obviare
being the Latin verb ‘to resist’.) A frame with a horizontal header would be
susceptible to stress fracture in the centre. The curves of an ogival arch, by
contrast, help to dissipate an enormous load to its lateral supports. Those 9th
century Muslims really were clever mathematicians.
Figure
48.2: Nested ogival arches above Seville Cathedral’s Door of the Prince
Copyright
© 2012 Paul Spradbery
The
ogival shape is not confined to architecture. Three-dimensional examples are commonly
found in aerodynamics and ballistics. If an object is to move efficiently,
through any medium, the shape of its ‘nose’ is crucial. Here, the streamlined ogive
comes into its own. Bullets are ogival, as are submarine casings, Japanese rail
locomotives and even suppositories. A wide range, for sure.
So,
keep an eye out for ogives. As I say, they are everywhere – in churches
especially (Figure 48.3), but even as garden features (Figure 48.4).
Figure
48.3: A delightful depiction of a 14th-15th century English church, complete
with ogival-arched windows
Copyright
© 2012 British Library Board
Figure
48.4: Not quite Seville Cathedral, but small-scale ogives can look good, too.
Copyright
© 2011 Paul Spradbery
In
case you were wondering, ‘ogive’ is pronounced ‘oh-jive’. I didn’t know,
either!
Copyright
© 2012 Paul Spradbery
