It seems that amongst the main industrialised countries, only the USA is hanging on to the Imperial system of measurement (OK, Britain typically has gone partially metric, but seems to be dragging it’s feet in some areas).
It seems incredible that we’re in the 21st Century and the world still doesn’t have a single system. Sadly, the issue became politicised in the early 80’s when Jimmy Carter tried to introduce metrication in America, and along came Ronald “We don’t need those tricky foreign metric systems here” Reagan, who made it a campaign issue (and of course won by a landslide), so this seems even further away than ever.
Of course, the imperial system has it’s advocates, so let’s examine the advantages. The units mostly have origins we can relate to. The inch is based on the width of a man’s thumb, and the foot clearly on the length of an average male foot. Of course these were often a matter of interpretation, and it’s interesting to note that the official definitions are now expressed as a fraction of metric units. The foot being defined as 0.3048 metres (exactly), and the inch as 2.54 cm (exactly).
Other units had similar origins… the furlong is the length of a furrow ploughed in a one acre (square) field. The acre came from the old English word ækre (probably taken from the Saxon Acker), meaning ‘open field’.
But the historic origins mean that the imperial system has a mix of multiples. There are 12 inches to the foot, 3 feet to the yard, 22 yards to a chain, 10 chains to a furlong, 8 furlongs to a mile. A mile is also 1,760 yards and 5,280 feet. In addition, there are 4,840 Square yards to the acre.
Then there’s the Imperial (Avoirdupois) system of weight… there are 16 drams to an ounce, 16 ounces to a pound, 14 pounds to a stone, 2 stones to a quarter, 4 quarters to a hundredweight, 20 hundredweights to a ton.
I recall that lot of time and effort was spent at school trying to commit all these multiples to memory!
In volume measurement, there are 4 gills to a pint, 2 pints to a quart, 4 quarts to a gallon. But here it starts getting really messy. The US system of volume measurement is 20% smaller. The multiples (above) are the same, but the US gill is 4 fluid ounces to the Imperial 5 fluid ounces.
Advocates of the imperial system are fond of quoting “A pint is a pound, the world around”, which makes me smile, as this is completely false! An Imperial pint is 1.25 pounds of water. Most people who grew up with Imperial measurement remember the saying “A pint of water is a pound and a quarter”. A pint is a pound ONLY IN THE USA, and even then only if the liquid is water. They should try weighing a pint of Mercury!
The metric system by comparison, is much more rational, based as it is on multiples of 10, 100 and 1,000. All you have to do is get you head around some of the terms and everything else is simple… milli means thousandth, but kilo mean a thousand. For example, a millimetre is a thousandth of a meter, but there are 1,000 metres in a Kilometre.
Furthermore the different systems (length, volume, weight, etc.) translate freely from one to the other. A centimetre is one hundredth of a meter (or 10 millimetres), and there are 1000 cubic centimetres to a litre (volume). A litre of water is 1 kilogram (weight), so a cube 10 cm on each side, if filled with water would contain 1 kilogram of water. So if you have a cubic meter of water, (that’s 10 x 10 x 10 litres), it’s a 1000 kilograms, aka. 1 metric ton (Tonne).
And if you have a square field 100 metres on each side (clearly 10,000 square metres)… your field is one hectare in area.
I know that some people like the fact that there are 12 inches to the foot, and this can be divided by 2, 3, 4 and 6. However it can’t be divided by 5, 7, 8 or 9 so I consider this to be a marginal (and arbitrary) advantage.
And given that a cubic metre of water weighs a metric ton; or 1000cc of water = 1 litre = 1 kilogram, then I’m inclined to ask defenders of the imperial systems if they know how many pints there are in a cubic foot, or how heavy a cubic yard of water would weigh. Not only would they (probably) not be able to do these calculations in their head, but I doubt that most people would even know how.
A single worldwide system will avoid the sort of problems experienced by Lockheed-Martin in 1999, where (incorrect) assumptions about the units caused the Mars Climate Orbiter to go into the wrong orbit and disintegrate. In 1983 a Boeing 767 ran out of fuel over Manitoba in Canada (see Gimli Glider) because of an incorrect conversion factor used to calculate the metric quantity of fuel. Both situations could have been avoided, and illustrate quite well the dangers when two different measurement systems come together.
Ultimately though, I think all you have to do is find someone who’s converted from Imperial to Metric, and is reasonably familiar with both, and ask the question: “Which is the best system?”; I doubt that you’d find many people defending the imperial system.
