Standards (Was: Metric essay)

[Raymond C Drouillard]

>>But I think one of these definitions may have changed recently
too---how
>>droll!! (Another droll one from the trolls at ISO!??!!) :-)

<snip>

>The definitions change to take advantage of better metrology.

<snip>

>Very few people will ever use the interferomtery standard, but when they
do,
>there is a standard so results can be compared.

<snip>

>You can't write down how to make a kilogram standard, you can only say
go to
>the french and compare your standard with theirs and adjust it to suit.
>
>(there are better ways to define the kilogram... but the primary
standard is
>still the french lump of metal).

-------------------------------------------------------------------------------------------



Of the Definition of Standards ...


The US Standard railroad gauge (distance between the rails) is 4
feet, 8.5 inches. That's an exceedingly odd number. 

Why was that gauge used?



Because that's the way they built them in England, and the US railroads
were built by English expatriates.

Why did the English people build them like that? Because the first rail
lines were built by the same people who built the pre-railroad tramways,
and that's the gauge they used.

Why did "they" use that gauge then? Because the people who built the
tramways used the same jigs and tools that they used for building
wagons, which used that wheel spacing.

Okay! Why did the wagons use that odd wheel spacing? Well, if they tried
to use any other spacing the wagons would break on some of the old, long
distance roads, because that's the spacing of the old wheel ruts.

So who built these old rutted roads? The first long distance roads in
Europe were built by Imperial Rome for the benefit of their legions.
The roads have been used ever since. And the ruts? The initial ruts,
which everyone else had to match for fear of destroying their wagons,
were first made by Roman war chariots. Since the chariots were made 
for or by Imperial Rome they were all alike in the matter of wheel 
spacing.

Thus, we have the answer to the original questions. The United States
standard railroad gauge of 4 feet, 8.5 inches derives from the original
specification (Military Spec) for an Imperial Roman army war chariot.
MilSpecs and Bureaucracies live forever.

So, the next time you are handed a specification and wonder what horse's
ass came up with it, you may be exactly right. Because the Imperial
Roman chariots were made to be just wide enough to accommodate the 
back-ends of two war horses.

Yet this standard may be even older. 4'8.5" in English measure is 5 pes
in Roman measure; the pes "foot" of 12 unciae "inches" was only about
11.3 inches in the later calibration. The reason that the English foot 
is longer than the Roman is that copies of copies of the standard 
measuring stick had become discrepant, so England restandardized 
by the royal appendage of King Edward I "Longshanks" (who apparently 
had some real clodhoppers at the end of his long shanks).

So the specification was based on a simple integer approximation, 2
equine rears = 5 human feet. Now, the two-horse war chariot was 
already a very obsolete style by Imperial times. Julius Caesar 
was amazed to find the Britons still fighting in these things 
(which they called "essed", a favorite word for some 
crossword-puzzle constructors). Both the Romans and the Britons 
had originally learned this style of war from Trojan War refugees:  
the losing side fled west to Italy (as romanticized in the Aeneid), 
Spain, and even out the Gibraltar straits to the British Isles
(the Danaans, from Argolis in Greece but on the "wrong" side of the 
war, are well documented in Ireland; and Britain is supposedly 
named for a Trojan leader). Thus, it is possible that the 
standard chariot with 5-foot wheel spacing goes back to Troy.

We are of course beyond the reach of reliable records, but it may well
be that US Standard Gauge is backward compatible all the way to Trojan
Milspec.

Part 2: All true. And perhaps instructive ...


Roman war chariots were set to 4'8.5" wheel spacing for a good reason,
and that reason, for the most part, still applied to horse-drawn
vehicles right up until mechanisation did away with horses. Up to 
that point, there was good reason not to change the standard, and 
no good reason to change it.

Even on the early plateways, even with mechanical locomotion, there 
was still good reason to keep the old gauge -- the jigs were already
available to make the wagons (and the wagons were originally 
horse-drawn models anyway), and no really good reason to change it.  
(One should note that these early plateways had the flange on the 
rail rather than the wheel, so the wagons could run both on roads and on
the
plateways.)

Up until railways were invented, wagons were mounted between their
wheels, partly for stability but mostly because large wheels are better
able to negotiate bumps in roads. Early railway wagons, although given
smaller wheels, were still mounted between the wheels. Steam locomotion
however meant that larger loads could be pulled, and increasing the
capacity of wagons became important. For a while no-one wanted to build
rolling stock that was too wide for fear of having it overbalance.
Instead, broaded gauges were used, up to 7'.

Broad gauges soon proved to have limitations in cornering at any kind of
speed, so the problem of overbalancing carriages was revisited, and it
was found that the narrower "standard" gauge could be used, with a 
decently wide carriage, and it still didn't matter if everyone sat on 
the same side of the carriage because the centre of gravity didn't 
move outside the wheels. Narrower gauges still could be used, at the 
expense of less stable rolling stock -- this was frequently done in 
hilly places where bends needed to be tight to negotiate tricky 
country.

In the end, standard gauge -- 4'8.5" -- prevailed, simply because the
alternatives, all the way down the ages, have not provided sufficient
reason to change.


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