Did the Romans build their aqueduct with bamboo? When the French drove on the left; Will the human race always need God?

The Romans built a 50km aqueduct from Uzès to Nîmes in France with an overall fall of about 17 metres and an average gradient of 1/3000. How did they determine the fall, and maintain the gradient during building?

In one word, the answer is probably . . . bamboo! A length of bamboo about 10-20cm diameter would make an accurate, jumbo-sized spirit level-come-theodolite.

Half-filled with water, it could be laid horizontally on trestles and used to lay out a levelling survey, all the way from Uzès to Nîmes. Using it like a telescope, they could use little buoys floating in the water at each end to sight a point a short way off. Stakes hammered into the ground would record the level at a given point, before the bamboo is moved to sight the next section.

Before doing this, the Romans would have had no way of knowing whether the planned route would be uphill or downhill. A team would have set out from both Uzès and Nîmes, each using a bamboo tube to sight a reasonably accurate contour along the sides of the valleys. When the teams met up they would see the elevation difference. Then the operation would be repeated, this time allowing a gradient deduced from the horizontal distance and the fall.

During the surveys the Romans would have spotted that an aqueduct at Pont du Gard would save a long detour. They knew the earth was a sphere, so the levelling operation (similar to those of the canal "navvies" in England during the 18th century) would need a correction to allow for the curvature of the earth to prevent the levelling measurement climbing slightly in both directions.

Richard Gosnell, Wootton Bassett,

Swindon, Wiltshire

Presumably the Romans used similar technology to that used by the English who built the New River from Hertfordshire to Islington in north London between 1609-13. This is longer, at 62km, and, with its end point only 5.8m lower than its start, less than a third as steep (if that's the word): the gradient is only one in 10,000. Quite a feat – and a bargain at £18,500, with no slaves to keep the cost down.

David Christmas, London N1

At a museum of fire appliances in France I was surprised to see all the pre-1945 machines were right-hand drive. These were not imports, but Renault, Citroën, and Delahaye. Why is this?

Before 1940 and the German invasion, the French drove on the left, as did the Scandinavian countries. France was also on the same time zone as Britain (the Greenwich meridian passes close to Paris). After the war the occupied countries retained the rule of driving on the right. Sweden, which was not occupied, retained driving on the left until the 1960s, when it seemed sensible to change to be in accordance with their neighbours.

An interesting hangover of this is that the US Virgin Islands were bought from Denmark in the 1920s. Despite being US territories, they still drive on the left, inheriting this from Denmark.

Geoff Mason, Warsash, Hants

In pioneering motoring days, when car and street lights were often disastrously feeble, some vehicle makers thought it prudent to stick the driver next to the kerb, the better to see vague carriageway edges and vulnerable pedestrians – especially if he was in a hurry, as drivers of fire appliances and racing cars usually were.

John Lilley, Brighton

Would it not have made more sense to ask someone at the museum?

Ian Payn, London SW6

Will the human race ever evolve beyond religion?

Probably not. Evolution relies on those features that result in more offspring; most religions seem to promote unceasing fecundity, so religious people tend to have larger families than the non-religious. Until social pressure or law limits family size and breeding, religion will be with us.

Stephen Booth, Birmingham

Some of it already has. They are called humanists.

Hilda Hayden, Malvern, Worcs

God willing.

James Hewitt, Los Angeles, US

No, because God is a good example of the survival of the fittest.

Nicholas Jacobs, London NW5

A Bombay duck is actually a fish. Are there any other misnomers of this kind?

Alan Beale asks who put the goose in gooseberry (N&Q, 30 June), but he has things the wrong way round. It has been known for so long that these sharp berries make the perfect accompaniment to rich, fatty meats that they are named by association. The French call them groseilles à maquereau.

Valerie Taylor, Bollington, Cheshire

Any answers?



Steve Lupton, Manchester

How different would the population of Europe be now if there hadn't been a second world war?

Nick Jenkins, London SE20

Why do you never see posh people at motorway service stations?

Alan Greenslade-Hibbert, Mollington, Oxon

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