# Steering a wrong course on the highways?

The Government’s reluctance to consider decimal measurement of distance on UK roads ignores a successful precedent at sea. (Article submitted by Derek Pollard).

It is often overlooked that the Romans introduced decimal measurement of distance to Britain. The Roman passus was the length of a double pace, left-right-left, and 1000 passus, or mille passus or gave us the mile. By the middle ages, this simple system had given way to one involving factors other than 10, such as 3, 8 and 22. And some of this medieval muddle was retained in 1824 when Parliament took a close look at weights and measures, and gave us the system that may be familiar to the older generation.

Long before this, sailors had realised that they needed something simple, and were not constrained by factors such as the distance a team of oxen could plough before needing a rest. So they came up with a more rational system of measurement.

Take a base unit of length (the fathom), have 100 of these in your next unit (the cable), and 10 of these in your largest unit (the nautical mile, although not the current international nautical mile). For speed, use your largest unit per hour, that is a nautical mile per hour or knot.

Such a simple system, but using the metre not the fathom as the base unit of length, has been rejected for the UK’s roads by successive Governments over the last 35 years. One wonders why. The principle, after all, served the Royal Navy well, and thereby the people of these islands, over several centuries.

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### One Response to Steering a wrong course on the highways?

1. Phil Hall says:

People think in tens perhaps more so than they realise. No body would say, for example, "there's a Post Office about 48 yards up the road"; No they'd say "about 50 yards up the road".

What is more the Government's own rules for distances in yards on road signs say it should be rounded to the nearest 10 yards. National speed limits are always multiples of 10 mph as well.

So why do we do this? There is no mathematical rule that says things should be estimated to the nearest ten or hundred of something. It is purely and simply because that's the way we count. The nearest ten or hundred or thousand etc fits naturally with this. It's far easier to concieve of progressively larger measurement units in the same manner.

The ancient mariners clearly recognised this and (without the baggage of trader's obscurations) ended up with tens and hundreds as as their scale factors.

I commend the above article as a good example of how we instinctly go decimal when we have a clean sheet and ease of use is the prime consideration.

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