ASIDES
Candlelight
Colin Ledsome CEng FIED considers
the lessons of the humble candle
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Wolfgang Zwanzger/stock.adobe.com
Candles have been around for several thousand years. An
essential cheap source of light, candles were fairly easy to
make. A ammable fat – wax – was melted and allowed to
solidify around a central ‘wick’, essentially an absorbent
piece of string. Historically cylindrical or slightly tapered, they are now
moulded in a range of shapes and are often scented.
The wick pokes out of the top and is lit by melting the wax within
it until the wax begins to burn. The heat of the ame melts more wax,
which ows up through the wick to keep the
ame going. A small pool of molten wax forms
where the wick enters the body of the candle,
forming a reservoir of fuel for the ame.
Most of the ame comes from the burning
wax, but as the candle begins to burn down,
the tip of the wick becomes too far from the
fuel supply, and itself burns away. For centuries,
this happened in the cooler red region at the
top of the ame, producing a black sooty smoke that settled on the
surrounding walls, ceilings, furniture and clothing. A large market for
wick-trimmers grew up.
It wasn’t until Victorian times that it was discovered that overtwisting
one of the strands making up the wick would make it curl over
as it emerged from the wax, and burn off in the hotter blue part of the
ame. This produced very little smoke, and wick-trimmers vanished
from shops. Soon after, gas lighting and then electric lights relegated
candles to decorative or symbolic purposes.
This seems to be a pattern followed by many everyday products.
A useful design is repeated even though it has some inconvenient
aspects. When a better solution is suggested, the old one is rethought
and upgraded with adaptations that could have been made much
earlier. Despite the last-ditch effort, the design gets superseded
anyway.
Four-sail windmills were easy to construct by crossing two wooden
spars to form the structure of the sails. Six-bladed windmills began to
appear when steam driven mills showed greater ef ciency, but couldn’t
keep up. Clay tablets were overtaken by paper and quill pens, which
were in turn replaced by fountain pens, then ball-points, felt tips, bre
tips and more. The pencil keeps going despite them all.
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