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November 2003

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Subject:
From:
Brian Ellis <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 5 Nov 2003 17:13:34 +0200
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Of course, this makes the metric system look stupid. It makes much more
sense to have 12 inches = 1 foot; 3 feet = 1 yard; 5.5 yards = 1 rod,
pole or perch; 4 rods, poles or perches = 1 chain (the length of a
cricket pitch between the wickets); 10 chains = 1 furlong; 8 furlongs =
1 statute mile. In summary, 1 mile = 8 furlongs = 80 chains = 320 rods,
poles or perches = 1760 yards = 5280 feet = 63360 inches. It is this
simplicity that dictates why printed circuits are largely dimensioned in
imperial measures, rather than the complex metric system. Similarly,
imperial weights, volumes, areas etc. are equally simple.

Brian

Ingemar Hernefjord (KC/EMW) wrote:
> The history of length and weight is funny to read
>
> examples pasted from english history article:
>
> The foot was declared one-third yard and the inch one thirty-sixth. King Edward II in 1324 recognising the Iron Ulna was not universally used declared "3 barleycorns, round and dry make an inch"
>
>
> Going as far back in time as Noah's ark, the lack of a universally understood unit of measurement was not a serious drawback. Most measuring was done by one craftsman completing one job at a time, rather than assembling a number of articles piecemeal to be put together later. It didn't make much difference how accurate the measuring sticks were or even how long they were. The cubit of Noah's time was the length of a man's forearm or the distance from the tip of the elbow to the end of his middle finger.
>
> For the United Kingdom, the basic English unit of length was the yard of three feet, or the fathom of six. Half a yard was the 18-inch cubit, and half a cubit was called a span, which was the distance across the hand from the tip of the thumb to the tip of the little finger when the fingers were spread out as far as possible. A hand was half a span. During the thirteenth century King Edward I decreed the 'Iron Ulna' after the bone of the forearm to become the main unit of measurement, which later became the 'yard'. He ordered a permanent measuring stick made of iron to serve as a master standard yardstick for his entire kingdom. King Edward realised that constancy and permanence were the key to any standard. The foot was declared one-third yard and the inch one thirty-sixth.
>
>
> Regards
>
> Ingemar Hernefjord
> Ericsson Microwave Systems
>
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of Brian Ellis
> Sent: den 4 november 2003 17:24
> To: [log in to unmask]
> Subject: [TN] OFF-TOPIC: Engineering Specs :-)
>
>
> Origins of engineering specs
>
>   Subject:  Origins of engineering specs and government
>   decisions. Ever wonder where engineering specifications come from?
>
>   The US standard railroad gauge (distance between the rails) is 4 feet,
>   8.5 inches, an exceedingly odd number. Why was that gauge used?
>   Because that's the way they built them in England, and the English
>   built the first US railroads.
>
>   Why did the English build them like that?
>
>   Because the first rail lines were built by the people who built the
>   pre-railroad tramways, and that is the gauge they used.
>
>   Why did they use that particular gauge then?
>
>   Because the people who built the tramways used the same jigs and tools
>   that they used for building wagons, which used the same wheel spacing.
>
>   Okay! Why did the wagons have that particular odd wheel spacing?
>
>   Well, if they tried to use any other spacing, the wagon wheels would
>   break on the old, long distance roads in England, because that's the
>   spacing of the wheel ruts in the granite sets.
>
>   So, who built those old rutted roads?
>
>   Imperial Rome built the first long distance roads in Europe (and
>   England) for their legions. The roads have been used ever since.
>
>   And the ruts in the roads?
>
>   Roman war chariots formed the initial ruts, which everyone else had to
>   match for fear of destroying their wagon wheels. Since the chariots
>   were made for (or by) Imperial Rome, they all had the same wheel spacing.
>
>   The United States standard railroad gauge of 4 feet, 8.5 inches is
>   derived from the specification for an Imperial Roman war chariot.
>
>   Specifications and Bureaucracies live forever.
>
>   The Imperial Roman war chariots were made just wide enough to
>   accommodate the back ends of two war-horses.
>
>   Now let's cut to the present...
>
>   The Space Shuttle, sitting on its launch pad, has two booster rockets
>   attached to the sides of the main fuel tank. These are solid rocket
>   boosters, or SRBs. A company builds SRBs at its factory in Utah. The
>   engineers who designed the SRBs wanted to make them a bit fatter, but
>   the SRBs had to be shipped by train from the factory to the launch site.
>
>   The railroad line from the factory has to run through a tunnel in the
>   mountains.
>
>   The SRBs had to fit through that tunnel, which is slightly wider than
>   the railroad track, and the railroad track is about as wide as two
> horses'
>   behinds.
>
>   So.... a major design feature of what is arguably the world's most
>   advanced transportation system was determined two thousand years ago
>   by a horse's ass.
>
>   Which is pretty much how most government decisions are made.
>
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