Metrication matters - Number 21 - 2005-02-10
Metrication matters is an on-line metrication newsletter for those actively involved, and for those with an interest, in metrication matters.
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1 Feedback - notes and comments from readers
3 Oddities - measurements from around the world
4 Tips - pointers and methods to make your measurements easier.
5 Signs of the times
7 Q&A - readers' questions and answers
8 Rule of thumb
10 Hidden metric
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I am quite excited at the prospect of travelling to the USA at the end of March as I have not been there since 1985; I will return to Australia in mid May. My itinerary will take me to Phoenix AZ, Denver CO, Salt Lake City UT, Midland TX, Charleston SC, and Los Angeles CA.
Whales can travel at about 70 metres per minute. This is a little less than your normal walking pace of 100 metres per minute. In a race, you could beat a whale any day.
Oven temperatures vary from cold to very hot, but few people memorise numerical values for these. Using degrees Celsius makes this simple and intervals of 20 °C seems to fit quite well with traditional oven descriptions.
120 °C is very slow
140 °C is slow
160 °C is moderately slow
180 °C is moderate
200 °C is moderately hot
220 °C is hot
240 °C is very hot
5 Signs of the times
In the last edition of 'Metrication matters' I wrote about the changing speed signs in Ireland and somewhat facetiously asked if the Irish were changing from the old Irish miles (2048 metres), old English miles (1609 metres) or some other kind of miles?
I received a comment from Tom Wade in Ireland that said, 'It is the speed signs that are changing on 2005-01-20 ... Signs will have an explicit 'km/h' on them. See http://www.gometric.ie for details ... The mile that we are currently replacing is the British Imperial mile (1609 m). Although I can dimly remember Irish perches/rods and miles being mentioned in primary school, they have not been used in formal measure for a long time. (Note: The Irish perch/rod was 7 yards rather than the British 5.5 yards, leading to the Irish mile being slightly longer).
Most of the change we think we see in life
Is due to truths being in and out of favor.
Robert Frost (1874-1963) 'The Black Cottage'
In your last newsletter you referred to a length of a cubit. Exactly how long is a cubit?
There is no definite length for a cubit. A cubit is the length from your elbow to the tip of your longest finger – it is about 450 millimetres, or for large people, such as myself, it is about 500 millimetres. When you are reading historical, or religious texts that refer to cubits be aware that the length of the cubits varied from individual to individual, from place to place, and from time to time. However there were some times when a government specified the length of a cubit and advertised its length by carving it in stone; an example is the Egyptian royal cubit that was used to build the pyramids.
8 Rule of thumb
An Australian, Jon Muir, walked 2500 kilometres from south to north in Australia a few years ago to raise money for charity. He walked alone, across the deserts and dry lakes during the southern winter. It took him 127 days, so his walking speed averaged 19.7 kilometres per day so we can guess that 20 km/day is a good rule of thumb for long distance walkers in hot dry conditions.
The story of Jon Muir's walk has been made into a movie that has been nominated for many international awards, see: http://www.everestnews2004.com/2004news/alone2005.htm
Sometime in the 19th century – after careful measurement – it was found that 1 imperial inch was 25.399 972 millimetres. The USA, in 1896, defined the USA inch by the relationship 1 metre equals 39.37 inches or 1 USA inch equals 25.400 050 8 millimetres.
Sometime between the two world wars the International Standards Association (ISA), which was the predecessor of the International Organization for Standardization (ISO) decided that the difference between the two inches was trivial and they created a new 'standard' inch where 1 international inch is exactly 25.4 millimetres.
This international (ISA) inch was adopted by the English-speaking nations after a conference in 1959 but this was not accepted universally in the USA. For example, the US Geodetic Survey announced that they would not change to the ISA inch because, they argued, that they would soon be changing to metric and that the discrepancy across the whole of the USA mainland was only a metre or two. In the interim, they would continue to use the old US standard foot and they would rename this as the 'survey foot'.
10 Hidden metric
The computer industry worldwide is clinging tenaciously to its description of screen sizes in inches – but which inches? Nowhere in the world is there a standard inch for computer makers to measure their screens. They all use the definition 1 inch = 25.4 millimetres because there is no inch standard. Every time computer sales people mention an inch they are indirectly referring to the millimetre standard, but they like to keep this hidden.
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Apparently his friend said, 'One of the best things I can do to encourage metrication in the USA and the rest of the world is to pass on a copy of "Metrication matters" to all of my friends with the suggestion that they subscribe.' What a compliment – Wheeee!
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