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Discovering Roman Technology

By Adam Hart-Davis

The Monty Python team pondered many big questions, among them: 'What did the Romans ever do for us?' Adam Hart-Davis rises to the challenge, investigating the innovations of the invaders. From roads to recipes, Adam looks at the lasting impact that Roman ingenuity still has in our lives today.

Adam Hart-Davis

Military might

When the Roman army invaded Britain in force in the spring of AD 43, they brought with them technology that must have astonished the native Celts. To begin with the Roman weapons were far better - they had good swords, spears, and several machines to throw missiles

The manuballista was a hand-cranked catapult that could hurl a bolt with an iron tip. This bolt whistled through the air at some 50 metres per second, and carried a terrifying punch; it would go through armour, and cause instant death.

The onager (named after a wild ass) hurled great rocks, which could demolish wooden buildings.

A manuballista (catapult)

The Roman armour was also superior; they had both chain mail, which might have been worn by the auxiliaries, though no one is quite sure, and also heavy armour made of overlapping iron plates that would stop anything short of a ballista bolt.

I watched a ballista being fired and was impressed by the sheer power and accuracy. I can well imagine the defending Celts surrendering quickly after seeing the force and accuracy of the Roman artillery.

Roman armour

We also constructed a repeating ballista, which fired bolts one after another automatically. On its first trial we were able to shoot eleven bolts a minute, which is almost four times the rate at which an ordinary ballista can be operated. If the Romans really used these they must have frightened the pants off the enemy, although they would also have used ammunition at a prodigious rate!

The Romans brought with them prefabricated forts. There is a reconstructed example at Lunt Fort near Coventry, complete with dovetail and cross-halving joints, cut elsewhere and simply fitted together on site for instant defence.

Roads and surveying

Blackstone Edge Roman road

In order to move the army quickly across the country, the Romans built tremendous roads. I had always been told that Roman roads are straight, but I really had this rubbed in on the A68 north of Corbridge, where the road goes in a dead straight line for miles over the rolling hills. In fact it's rather dangerous for driving; because it is so straight you are tempted to drive fast. Nothing in the Roman world did more than say 20 m.p.h. (a galloping horse) and they built their roads up and down steep hills - sometimes as much as 1 in 6.

'There's an old saying 'I hear and I forget; I see and I remember; I do and I understand.''

The result is that not only are there some fierce hills to climb, but often there are blind summits, where you can't see oncoming traffic even 50 yards away. So if you drive too fast and try to overtake you are liable to meet someone else coming the other way.

Building roads in a straight line is not difficult - you merely have to plant two canes in the ground, walk ahead and plant a third in line with the first two, and so on. Sighting along canes gives good straight lines for miles. However, what really impressed me was how they managed to set off in the right direction. For example, when the Romans wanted to build a road from London to Chichester, they knew exactly where to head for, even though the distance is 65 miles, there are several hills in the way and they had neither maps nor compasses.

There's an old saying 'I hear and I forget; I see and I remember; I do and I understand.' Roman road surveying was just like this for me. I learned and understood how to do it by surveying a route over high sand dunes from one flag to another that I could not see. I knew roughly which way to go; so I went to the high point on a sand dune not far from the route and put a beacon there. Then I walked on and planted another beacon at the next high point, from where I could see the goal. I went back to the first beacon and moved it to the straight line between the first flag and the second beacon by using a groma.

The groma was the standard Roman surveyor's instrument. It's an upright stick with a couple of bits of wood fixed to the top to make a cross. From each end of the cross hangs a little weight on a string. When the groma is stuck in the ground you stand behind it and twist it until you can sight along two of the strings to the starting point. Then you walk around the groma and sight the other way, to the second beacon. If the strings do not line up with the beacon then you move the beacon beside you in order to get more in line. Plant the beacon, plant the groma, and try again, until the strings line up with the start point in one direction and with the second beacon in the other. Then you know that the start point and the first two beacons are all in one line.

Repeat the whole process with the second beacon, then with the first again, and the second again, until the start point, the finish point, and both beacons are in the same line. This process would be much more efficient if one surveyor were standing at each beacon, ready to move it - and even better if they all had mobile phones!

Codes and signals

Two groups of five signal flags

The Romans had clever signalling systems. On Hadrian's Wall an alphabetic system was used based on two groups of five flags, which allowed them to send messages letter by letter, and was similar to the system developed in England at the end of the eighteenth century. (The Irishman Richard Lovell Edgeworth is supposed to have invented a telegraph system in order to get the racing results from Newmarket before his bookmaker - but he never developed it!)

A list of codes

The Romans also had a coded system, with which they could send only one of a dozen fixed messages, depending on the time for which they showed a flag. The sender and receiver would have the same code book and identical water clocks, marked perhaps with numbers. To send message VI in the book, raise your flag (or flaming torch at night), wait until the receiver raises a flag to acknowledge, then lower your flag, and raise it again, starting your clock as you raise the flag. When your flag points to VI, lower your flag again. The receiver should have started the clock when the flag went up for the second time, and stopped it when the flag went down; the number VI will reveal the message.

The idea of using codes like this was taken up by the French, also at the end of the eighteenth century.

Food and baths

A Roman meal

However, Roman technology was not entirely concerned with military action. The Romans brought with them a whole way of life that in due course the Britons adopted with enthusiasm.

Celtic cooking had probably been a one-pot affair, such as a mess of potage to be shared by the household, but the Romans introduced the three-course meal.

A pudding made with fish sauce

They cooked meat, fish and eggs and brought with them apples, pears, apricots, turnips, carrots, coriander and asparagus. They brought recipes too - I can strongly recommend the kidneys stuffed with herbs and the fishy custard.

There are still the remains of the flushing lavatories that the Roman soldiers used at Housesteads on Hadrian's Wall, and at Bath you can still see a lead pipe that seems to have carried water under pressure to a sort of whirlpool bath. The word plumbing comes from the Latin word plumbum, meaning lead.

A strigil

The Romans were keen on bathing, but I discovered that most of the business of bathing was for pleasure and recreation, rather than for keeping clean. To clean off the dirt they went through a hot room in the baths, like a sauna or a Turkish bath, and then rubbed oil on their skin, and scraped off the mucky mixture of oil, sweat, and dirt, using a curved metal scraper called a strigil. I tried this out and found it remarkably effective, although I don't quite know how they managed to clean their backs - I think I would rather have a slave do it. Apparently Roman ladies used to collect the sweaty gloop from athletes and gladiators and use it in a face pack - but no one offered to try mine!

The wonderful wheel

The Roman waterwheel

A waterwheel was built by Henry and John Russell in an attempt to copy the remains of a wheel at Dolaucothi in Wales, which appears to have been used to pump water out of the gold mine.

The reconstructed wheel was twelve feet high and one foot wide, and when I got it going by walking up the outside like a treadmill, I was able to lift a bathful of water - 150 litres - every minute. According to the experts this is about twice the amount the Romans would have lifted. However, I'm a heavy chap and was only just able to lift this much water. A puny British slave of 1800 years ago certainly would not have been heavy enough.

'The big cogwheel rotated exactly once every Roman mile, and at this point a small stone - a calculus - dropped into a box.'

A Roman odometer

Therefore it seems likely that the Roman wheel was only about eight inches wide, rather than a foot. Also I could only operate the wheel for a couple of minutes before collapsing for a rest, whereas the slave would probably have been expected to carry on for hours, even in the dark and underground.

Roman latrines

The Russell brothers also built the most wonderful wine press, a Roman fire pump, with which we managed to put out a small fire, and weirdest of all a Roman odometer, to measure the distance travelled along a road. Each time the four-foot wheel turned, it engaged once with a cogwheel carrying 400 teeth. This meant that the big cogwheel rotated exactly once every Roman mile, and at this point a small stone - a calculus - dropped into a box. So at the end of the trip count the calculi and you know how many miles you have covered!

I am amazed at how efficient the Romans were as engineers and organisers. They were not brilliant innovators, and in the 400 years that they occupied Britain they failed to make many technological advances. However, the might of the Roman empire stemmed from the brilliant use they made of the technology they brought with them. And for me, pride of place among the technology must go to that waterwheel at Dolaucothi and those latrines on Hadrian's Wall.

Find out more

Books

The Classical Cookbook (British Museum Press)

Cultural Identity in the Roman Empire edited by Ray Laurence and Joanne Berry (Routledge, 2001)

Ancient Rome and the Roman Empire by Michael Kerrigan (BBC Consumer Publishing, 2001)

Discovering Roman Technology

Military might

Roads and surveying

Codes and signals

Food and baths

The wonderful wheel

Find out more

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