People wander onto my sites with the strangest requests. A woman walked in recently looking for a piece of timber to put under the wheel of her fridge. She explained the floor was out of level and she needed a board 80 long.
Now 80 to a builder means 80mm and so I dutifully cut her a piece and handed it over. She blushed, expecting a long thin board 80 centimetres long that would fit under the two front wheels of her fridge! It is a curious anomaly that the building industry does not use centimetres. Builders deal solely in millimetres and metres.
Why metric is great
Can you imagine what the black areas on this map have in common? Apart from very ordinary rates of infant mortality these are the few places in the world resisting a change to metric measurements.
Metric has three massive benefits
1. Its is scalable
It is scalable, so the lyrics to “Fortunate Son” by John Fogerty may be a few bytes, the song will run to kilobytes on iTunes, the album may stretch to megabytes and your iTunes library is measured in Gigabytes. Each step bears a very distinct relationship that is as easy to follow as a dollar and cents.
2. One unit for each kind
Metric uses a single unit for all measurements of a certain kind. So we can forget multiple units like sand in cubic yards, fridges in cubic feet and dams measured in thousands of gallons. Metric would measure all these in cubic metres.
I haven’t even got to square perch (which sounds like a protestant bar stool) or tons per township ( Put up the roadblocks Tim , they’ve reached their bullshit tonnage for this month) and I will leave hand pound per second to your imagination
3. Its is a decimal system.
It is easy to comprehend that .31 of a dollar is less than .38 dollar, rather than the alternative 5/16 and 3/8 of a dollar. It is childs play to add .31 and .38 dollars and not much harder to multiple or divide them. The same cannot be said of multiplying 5/16 x 3/8. (The answer is two bushels and threepence)
To this list I would add the units have a real world basis.
- A litre of water has a mass of one kilogram
- A litre of water occupies 1000 cubic centimetres
- A cubic metre of water weighs one tonne
In the building industry these relationships have many everyday uses, such as when we consider the weight of a hot water tank being installed on a roof, or ponder the volume of a water tank that needs to have a certain sized footprint to fit in a narrow sideway.
The Imperial or English system of measurement is seriously quirky. In many cases it is not a system at all but rather an unrelated collection of curious historical units . A league was the distance a man could walk in an hour, presumably not whilst being chased.
These units also lack a consistent base which is very problematic, consider this
- 12 inches in a foot
- three feet in a yard
- eight inches in a link (give or take)
- 100 links in a chain
- 10 chains in a furlong
- 8 furlongs in a mile
- 3 miles in a league.
- I’m not making this up.
Six feet is good and tall!
One argument raised in defence of the old system of measurement is that people can relate to the units. So we consider a six foot man to be tall.
As I am six feet tall this seemed like a great height to divide the world. Years later however, with two sons who tower over me, it seems a fairly arbitrary division!
Strangely we still hang onto a number of these idiosyncratic measurements, consider 50 inch televisions, seven inch heels and eight pound babies!
At the time metric was adopted in Australia the building industry was awash with curious dual scale rulers , where imperial lengths could be scaled from metric drawings. This was so that builders who had a feel for 3 foot 2 inch hallways and 15 feet wide living areas could get a sense of their metric equivalents. This is however just a question of experience. I have learnt all these same standard dimensions in metric, so that I would baulk at design with a toilet stall that was 1400 long or approve a master bedroom that was 3.9 metres wide.
Eight and three sixteenths full!
The millimetre is a very good unit of measurement for building trades and it involves all the accuracy that we are ever likely to need. We do not need the fine tolerance of a mechanic’s feeler gauges, measured in thousandths of an inch. When I was training I worked with a carpenter who liked to divide sixteenths of an inch into smaller units. He would ask me to cut a piece of timber, eight and three sixteenths full. He was in essence measuring to millimetre accuracy.
Changing from English to metric
So is it hard to change an entire country from Imperial to metric? I grew up in a house were oven temperatures and cooking measurements were taped to the back of our pantry door. The cooks in my family were mixing ingredients and calculating cooking times in metric whilst working from recipes that called for ounces of butter and minutes is a slow oven. They coped well in a field were precision is less important than feel.
My older brother Simon had two significant challenges during his school days. Australia moved away from pounds, shilling and pence to dollars and cents, and a few years later he had to unlearn feet and inches and pick up the new fangled metric system. It was all millimetres, centimetres and metres. The new paradigms were not difficult for him but he was frustrated at having to spend a lot of time learning the various conversion factors.
The actual adoption, whilst expensive, was relatively simple. Whenever this question is raised the cost of changing roadside speed signs is always quoted in millions of dollars. This is however probably the simplest change to make. The cost of altering texts, tools, instruments and parts would be far more problematic. In the Australian case metric started to appear in school texts for years before the eventual change. Instruments and gauges were recalibrated to show dual measurements. The actual change was done over an extended period of time. We had adopted metric as an official system in 1947, but it took until the mid seventies to fully implement it.
Our Americans cousins are the only significant country not going metric. They passed a Metric Bill in 1975 and so SI units of measure are legal in the States, but just not generally used. The American military, medical system and significant parts of their industry are all metric. They are typically metric were they interact with Europe and the rest of the World.
NASA has adopted metric, as is befitting the leading space agency in the world. This however had disastrous consequences, as reported by CNN
NASA lost a 125 million Mars orbiter because a Lockheed Martin engineering team used English units of measurement while the agencys team used …..metric
A simple conversion of outdated imperial units used by Lockheed caused the Orbiter to strike the Martian surface at excessive speed.
One of the last hold outs in a the push toward metric is the American building industry. The lure of inches for lumber and lengths in feet is seemingly irresistible. (it is even curious that the Americans call that timber a 2X4, where in Australia it was a 4X2) To avoid the confusion from my woman with her out of level fridge the Australian building industry declared.
The metric units for linear measurement in building and construction will be the metre (m) and the millimetre (mm), ….. This will apply to all sectors of the industry, and the centimetre (cm) shall not be used.’
We banished the centimetre as some defacto inch measurement and have never looked back.
It speaks volumes about the US that they believe in some unalienable right to an outdated, and uniquely strange system of measures in this current millennium.
As Mark Twain put it;
Denial ain’t just a river in Egypt.
