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Roman Engineering Tricks
10 Cool Engineering Tricks the
Romans Taught Us
BY GALLAGHER FLINN
Some stuff the ancient Romans
were good at -- other stuff they weren't.
In terms of the abstract
sciences and literature, they were always in the shadow of their Greek
neighbors.
Their poetry never
reached the same heights, their philosophies of Stoicism and Epicureanism were
borrowed, and anyone who's ever used Roman numerals knows how difficult the
system was even for even simple arithmetic.
If you wanted someone to
explain geometry, you asked a Greek.
If you wanted someone to
build you a floating bridge, a sewer network or a weapon that could fire
flaming balls of gravel and tar 300 hundred yards (274 meters), you called a
Roman.
As much as the Greeks gave
us, Rome's brilliant architectural, organizational and engineering feats that
make them stand out among the ancient peoples.
Despite the fact that their
knowledge of math was rudimentary, they constructed models, experimented, and
built as sturdily as possible to compensate for their inability to calculate
for stress and weight.
The result is a set of
edifices and architectural achievements that stretch from the Limyra Bridge in
Turkey to Hadrian's Wall in the United Kingdom.
With so many brilliant
examples, many of which are still in excellent condition, it's hard not to have
picked up a few pointers about how to build structures that last.
Read on for 10 of Rome's
coolest engineering feats.
10 The Dome
We take interior space for granted
in the modern world, but we shouldn't.
Our enormous vaulted arches,
huge atriums (a Latin word, by the way), hollow steel and glass skyscrapers,
even a simple high school gymnasium -- all of these structures were
inconceivable in the ancient world.
Before the Romans perfected
dome-building, even the best architects had to deal with the problem of a heavy
stone roof, forcing them to crowd the floors of temples and public buildings
with columns and load-bearing walls.
Even the greatest
architectural achievements before Roman architecture -- the Parthenon and the
Pyramids -- were much more impressive on the outside. Inside, they were
dark, confined spaces.
Roman domes, by contrast,
were spacious, open and created a real sense of interior space for the first
time in history.
Stemming from the realization
that the principles of the arch could be rotated into three dimensions to
create a shape that had the same supportive power but an even larger area, dome
technology was mostly due to the availability of concrete, another Roman
innovation that we'll discuss later in this article.
This substance was poured
into molds on a wooden scaffolding, leaving the hard, strong shell of the dome
behind.
9 Siege Warfare
Like a lot of technology,
Roman siege weaponry was mostly developed by the Greeks and then perfected by
the Romans.
Ballistae,
essentially giant crossbows that could fire large stones during
sieges, were mostly back-engineered designs from captured Greek weapons.
Using loops of twisted animal
sinews for power, ballistae worked almost like springs in giant mousetraps --
when the sinews were tightly wound and then allowed to snap back, they could
launch projectiles up to 500 hundred yards (457 meters).
Since it was light and
accurate, this weapon could also be fitted with javelins or large arrows and
used to pick off members of opposing armies (as an anti-personnel weapon).
Ballistae were also used to
target small buildings during sieges.
Romans also invented their
own siege engines called onagers (named after the wild donkey and
its powerful kick) to fling larger rocks.
Though they also used springy
animal sinews, onagers were much more powerful mini-catapults that fired a
sling or a bucket filled with either round stones or combustible clay balls.
Though they were much less
accurate than ballistae, they were also more powerful, making them perfect for
blasting down walls and setting fires during sieges.
8 Concrete
As far as innovations in
building material go, a liquid rock that's both lighter and stronger than
regular stone is hard to beat.
Today, concrete is so much a
part of our daily lives that it's easy to forget just how revolutionary it is.
Roman concrete was a special
mixture of rubble, lime, sand and pozzolana, a volcanic ash. Not only could the
mixture be poured into any form you could build a wooden mold for, it was much,
much stronger than any of its component parts.
Though it was originally used
by Roman architects to form strong bases for altars, starting in the 2nd
century B.C., the Romans began to experiment with concrete to produce more
freestanding forms.
Their most famous concrete
structure, the Pantheon, still stands as the largest unreinforced concrete
structure in the world after more than two thousand years.
As we mentioned earlier, this
was a major improvement on the old Etruscan and Greek rectangular styles
of architecture, which demanded heavy walls and columns everywhere.
Even better, concrete as a
building material was cheap and fireproof. It could also set underwater and was
flexible enough to survive the earthquakes that plague the volcanic Italic
Peninsula.
7 Roads
It's impossible to mention
Roman engineering without talking about roads, which were so well-constructed
that many of them are still in use today.
Comparing our own asphalt highways
to an ancient Roman road is like comparing a cheap watch to a Swiss version.
They were strong, precise and built to last.
The best Roman roads were built
in several stages. First, workers dug about 3 feet (0.9 meters) down into the
terrain where the planned road would be. Next, wide and heavy stone blocks were
set in the bottom of the trench and then covered with a layer of dirt or gravel
that would allow drainage.
Finally, the top layer was
paved with flagstones, with a bulge in the center for water to run off.
In general, Roman roads were
about 3 feet (0.9 meters) thick and enormously resistant to the ravages of
time.
In typical Roman fashion,
engineers of the Empire insisted on using straight lines for their roads
primarily and tended to push through obstacles rather than building around
them.
If there was a forest, they
cut it. If there was a hill, they tunneled through it. If there was a swamp,
they drained it.
The drawback, of course, to
that type of road building is the enormous amount of manpower required, but
manpower (in the form of thousands of slaves) was something that the ancient
Romans always had in spades.
By A.D. 200, there were more
than 53,000 miles (85,295 kilometers) of major highways crisscrossing the Roman
Empire [source: Kleiner].
6 Sewers
The great sewers of the
Roman Empire are one of the oddities of Roman engineering in that they weren't
exactly built to be sewers in the first place -- as immense and complex as they
were, they weren't so much invented as they just sort of happened.
The Cloaca Maxima (or
Biggest Sewer if you want to translate it directly) was originally just a
channel built to drain some local marshes.
Digging commenced around 600
B.C., and over the next 700 hundred years, more and more waterways were added.
Since more channels were dug
whenever it was deemed necessary, it's hard to tell when the Cloaca Maxima
stopped being a drainage ditch and became a proper sewer.
Primitive though it was
initially, the Cloaca Maxima spread like a weed, stretching its roots deeper
and deeper into the city as it grew.
Unfortunately, because the
Cloaca Maxima drained directly into the Tiber, the river became absolutely
swollen with human waste.
That's certainly not an ideal
situation, but with their aqueducts, the Romans didn't need to use the Tiber
for drinking or washing.
They even had a goddess to
watch over their system -- Cloacina, the Venus of the Sewer.
Perhaps the most important
and brilliant innovation of the Roman sewer system is the fact that it was
(eventually) covered, cutting down on disease, smells and unpleasant sights.
Any civilization can dig a
ditch to go to the bathroom in, but it takes some impressive engineering to
monitor and maintain a sewer system so complex that Pliny the Elder even
declared it more stupendous than the Pyramids as a monument to human
achievement.
5 Heated Floors
Controlling the temperature
in any building efficiently is one of the hardest engineering tasks humans have
had to deal with, but the Romans had it solved -- or at least, almost solved.
Employing an idea that we
still use to this day in the form of radiant heat flooring, hypocausts were
sets of hollow clay columns spaced every few feet below a raised floor through
which hot air and steam were pumped from a furnace in another room.
Unlike other, less advanced
heating methods, hypocausts neatly solved two of the problems that have always
been associated with heating in the ancient world -- smoke and fire.
Fire was the only available
source of heat, but it also had the unfortunate side effect of burning down
buildings from time to time, and smoke from an indoor flame can be deadly in a
closed space.
However, because the floor
was raised in a hypocaust, hot air from the furnace never actually came
into contact with the room itself.
Rather than entering the
room, the heated air was piped through hollow tiles in the walls. As it passed
out of the building, the clay tiles absorbed the heat, leaving the room itself
steamy and Roman toes toasty warm.
4 The Aqueduct
Along with roads, aqueducts
are the other engineering marvel that the Romans are the most famous for.
The thing about aqueducts is
that they're long. Really long.
One of the difficulties of
watering a large city is that once the city gets to a certain size, you really
can't get clean water from anywhere near it.
And though Rome sits on the
Tiber, the river itself was polluted by another Roman engineering achievement,
their sewer system.
To solve the problem, Roman
engineers built aqueducts -- networks of
underground pipes, above-ground water lines and elegant bridges, all
designed to channel water into the city from the surrounding countryside.
Once in Rome, water from the
aqueducts was collected in cisterns before being distributed to the fountains
and public baths the Romans loved so dearly.
Just like their roads, the
Roman aqueduct system was incredibly long and complicated. Though the first
aqueduct, built around 300 B.C., was only 11 miles long, by the end of the
third century A.D., Rome was supplied by eleven aqueducts, totaling more than
250 miles in length.
3 Water Power
Vitruvius,
the godfather of Roman engineering, describes several pieces of technology that
the Romans used for water power.
Combining
Greek technologies like the toothed gear and the water wheel, Romans were able
to develop advanced sawmills, flourmills and turbines.
The
undershot wheel, another Roman invention, rotated under the force of flowing
(rather than falling) water, making it possible to build floating waterwheels
to grind grain supplies.
This
came in handy during the siege of Rome in 537 A.D., when the defending general,
Belisarius, solved the problem of the Gothic siege cutting off food supplies by
building several floating mills on the Tiber to keep the populace supplied with
bread.
Strangely,
archaeological evidence suggests that though Romans had the mechanical
expertise necessary to build all sorts of water-powered devices, they did so
only rarely, preferring cheap and widely available slave labor instead.
Nonetheless,
their watermill at Barbegal (in what is now France) was one of the largest
industrial complexes in the ancient world before the Industrial Revolution,
with 16 waterwheels to grind flour for the surrounding communities.
2 The Segmental Arch
Like almost all of the
engineering feats we've listed, the Romans didn't invent the arch -- but they
sure did perfect it.
Arches had been around for nearly
two thousand years before the Romans got a hold of them.
What Roman engineers realized
(quite brilliantly, as it turned out) was that arches need not be continuous;
that is, they don't have to span a gap in one go.
Instead of trying to cross
gaps in one great leap, they could be broken up into several, smaller sections.
Turning an arch into a
perfect semicircle wasn't necessary so long as each section had struts
underneath. That's where the segmental arch came in.
This new form of
arch-building had two distinct advantages.
First, because the arches
could be repeated rather than having a single stretch across a gap, the
potential distance for a bridge span could be increased exponentially.
Second, because less material
was required, segmental arch bridges were more amenable to the flow of water
underneath them.
Instead of forcing water
through a single small opening, water under segmented bridges could flow
through freely, reducing both danger of flooding and the amount of
wear on the supports.
1 Pontoon Bridges
Roman engineering was mostly
synonymous with military engineering.
Those roads that they're so
famous for weren't built so much for day-to-day use (though they were, of
course, useful for that) as for marching legions quickly into the countryside,
hitting trouble spots and getting out again.
Roman-designed pontoon
bridges, constructed mostly during wartime for the shock and awe of quick
raids, served the same purpose and were a specialty of Julius Caesar's.
In 55 B.C., he built a
pontoon bridge that was around 437 yards (400 meters) long to cross the Rhine
river, which was traditionally thought by the Germanic tribes to be safely out
of reach of Roman power.
Caesar's Rhine bridge was
clever for a couple of reasons.
Building a bridge without
diverting a river is notoriously difficult to do, and even more so in a
military setting where construction must be guarded at all times, so engineers
had to work fast.
Rather than driving beams
straight into the river, engineers rammed timbers into the bottom of the river
at an angle against the current, lending the foundation extra strength.
Protective pilings were also
driven in upstream to catch or slow down any potentially destructive logs that
might float down the river.
Finally, the beams were
lashed together, and a wooden bridge was built on top of it.
In total, the construction
took only ten days, used entirely local lumber and sent a firm message to local
tribes about the power of Rome: if Caesar wanted to cross the Rhine, he could
do it.
There's also the possibly
apocryphal story of Caligula's (yes, that Caligula) pontoon bridge built across
the sea between Baiae and Puzzuoli, a roughly 2.5-mile (4-kilometer) span.
Supposedly, Caligula
commissioned the bridge because a soothsayer had prophesied that he had roughly
the same chance of becoming emperor as he did of crossing the bay of Baiae on a
horse.
Never one to practice
restraint, Caligula allegedly took it as a dare, lashed a chain of boats together,
covered them with dirt and went for a ride.
