Crazy acres
Of all the traditions that are kept alive today the acre for land measurement has to be one of the daftest.
To begin with hardly anybody today really knows what an acre is let alone where it came from. Yet we see and hear it being quoted all the time in respect of land area both for housing and even industrial purposes.
So what is an acre? Well anyone could look it up in a table of conversions and find it listed as 4840 square yard, but why this peculiar number? Furthermore how come it isn’t a square number? (The square root of 4840 = 69.5701085 …)
It is in fact the area of a strip of land 1 chain wide by 1 furlong in length, where a chain is 22 yards and a furlong is 10 chains (hence 22 x 220 = 4840). According to popular history this is an estimate of how much land a farmer could till in a day with a horse drawn plough. Now that the reader knows this I’m sure it’s relevance to modern applications will become clear!
The proper metric unit of area is of course the square metre, but since it is rather small for land area of any size a unit known as the hectare has come into general use. It is quite simply a square 100 m by 100 m The name derives in fact from a contraction of the prefix hecto (x 100) applied to another metric unit of area known as the ‘are’ (prounced air) which is a square 10 m by 10 m This latter unit is rarely used nowadays.
The arithmetic is remarkably logical and simple. 100 square metres = 1 are, 100 are = 1 hectare, 100 hectare = 1 square kilometre.
With the demise of the ‘are’ the hectare is now better known as being 10 000 square metres.
The sadest thing of all about the retention of the acre is that it does nothing to help people understand the concept of area and how we measure it. Nothing could be more awkward than a rectangle 10 times as long as it is wide as means of guaging it even if that fact is known.
In truth it is more likely that when information about modern developments are quoted in acres it has actually been worked out in hectares and converted using the factor 1 hectare = 2.47 acre. A classic case of taking something easy and making it hard.
March 29th, 2007 at 08:52
When I was a young town planning assistant in the 1960s, one of my most tedious jobs was measuring the areas of building sites in square feet (not yards, by the way), converting these sums into acres and then, as a check, aggregating them into grid squares on the 1:1250 scale ordnance survey sheet. The instrument used was a “planimeter”, which required a conversion factor according to which scale you were working at. All this was done manually by long multiplication and division (there were no electronic calculators, let alone computers in those days - although a slide rule could be used for approximations). As there are 43 560 sq ft in an acre, and 640 acres in a square mile, the horrendous nature of the calculations can be imagined.
I was overjoyed therefore when I learnt that the UK was to convert to metric system by 1975, and we could adopt the logical simplicity of square metres, hectares and square kilometres. What bliss!
Sadly, owing to the timidity and political cowardice of our politicians and civil servants over the last 42 years, we are still stuck with the mess of two systems of measurement, and very few people could even begin to calculate an area of land in either acres or hectares. What an indictment of a supposedly modern country!
March 29th, 2007 at 10:37
The Scottish acre was standardised in 1661 and abolished in 1824. It had an area of 4870 m² instead of the English acre’s 4047 m². It is also worth noting that the German word for a “field” is “acker”.
The abolition of the Scottish acre was part of a standardisation of weights and measures that was being carried out by the British Government at the time – the Imperial Gallon dates from that era. Unfortunately the British Government was run by people who today would be called “Eurosceptics” and who appeared to by trying to develop a “British decimal system” – why else would the gallon be defined as the volume of 10 lbs of water? The British Government cannot plead ignorance – four years previously across the North Sea, the Dutch, on realising that every city had its own “voet” (foot) and “pond” (pound), had standardised on the metric system.
April 2nd, 2007 at 19:24
Acres are one of those strange measures, like “size of a football pitch”, that crop up in the media, and I have no idea how big either is. Therefore I’m somewhat disappointed that a pro-metric website is trying to force the arcane numbers that seemingly define an acre into my head: I have no room for such trivia! The whole point of the metric system is that you do not *need* to waste time recalling random numbers to work out how large something is.
All I need to know is that the definition of an acre is indeed arcane (and certainly not a nicely-square unit of area in its simplest form) and a reminder that we do have perfectly sensible - and easily-convertible - units of area: the m², the hectare, and the km².
So the question is, why doesn’t the media use hectares as a description more often? As a simple 100×100 m square, it can be easily visualised and understood. And as the author notes, 10x 10 hectares = 1 km², what could be simpler?
April 3rd, 2007 at 09:11
In response to David, I don’t think this article is trying to fo”force arcane numbers” into your head, but illustrate just how daft this particular measure is. I too am also frustrated by media reports that compare things to the “size of a football pitch”, especially since British football pitches aren’t (or at least never used to be!) the same size, unlike the US “Football Field” which, like in most US professional sports, is a fixed size.
I spent a couple of days last week scanning through a number of news stories on the BBC news web site and found no consistency in the way that they use acre and hectare, but this is the same in the real world where you can drive past commercial construction sites to see billboards advertising warehouse space, some in square metres and others in square feet. If I were looking for space to run a business I’m sure I’d be quite bemused at having to keep converting from one to the other to make comparisons. On the same basis it’s no wonder that we have to use comparisons like football pitches, busses and jumbo jets so that joe public can get a feel for the size of an object… no sooner than people get used to what a metre looks like, the next thing they know is that they’re being bombarded with feet again!
I think this all goes to prove that unless we have legislation to force the use of one type or measurement, even if it’s only temporary, this mess will just continue!
May 1st, 2007 at 18:39
An are (a) is a square dekametre (dam²) and a hectare (ha) is a square hectometre (hm²), by the way, and a centiare (ca) is a square metre (m²).
May 13th, 2007 at 23:56
I visualize an acre as 4000 m^2. Since it was originally defined as an area of land that can be ploughed in a day, then there is no reason it can’t be thought of as a nice rounded number in metric. This can easily be thought of as any number of combinations of metres by metres.
A 50 x 80 m plot would be the closest to a square using rounded numbers.
I live on a typical one quarter acre lot in a suburban sub-division. this would be a 1000 m^2 lot. I measured it once with a tape measure and it was very close to 20 m 50 m.
It seems the acre might work better with metric then with FFU.
I wonder if those who cling to FFU do so because they like the names. So why not recycle the names as slang terms for metric units. Yards and quarts can disappear and be replaced by metre and litre. There is no need to have two units for the same name.
A pound can be 500 g, a mile can be 2 km, a pint 500 mL (a good compromise between the US and UK version), a gallon can be 5 L, etc. The old units names are still found in other EU states but the old meanings are long gone. If the UK followed the practice of the Continent in regards to old unit names, then there might not be such a fuss.
Who quibbles when they go to France and gets 500 g when a pound (livre) is requested, or 500 mL when a pint is requested? So why should they quibble if it is done in the UK?
July 18th, 2007 at 21:55
Does this mean that Winnie the Pooh will now live in the ‘40.46 Hectare Wood’? I hope not!
October 13th, 2007 at 13:54
I have to say, I chanced upon this looking for a converter: square metres to acres - and it’s fantastic I did.
I’m from Australia where the acre has already invaded the land and real estate industries, and sadly society’s consciousness.
And yet now, thanks to you Phil Hall, it all makes such simple sense.
Out with the acre - it seems so ridiculous that it is used.
Bring back the hectare - 100 m x 100 m!!
Great article!!
May 26th, 2008 at 23:25
As an expat Brit living in the US, I’m back in the world of imperial measurements in official, not just conversational use. And since Americans love talking about land and house lots and other property-related guff, I have to plead ignorance. I’m in my mid-30s, and it’s taken me until now to visualise an acre.
(Basically, think ‘a bit bigger than half a UEFA-approved football pitch’.)