why standard gauge (again)

[G.Lambert@unsw.edu.au (Geoff Lambert)]

In light of recent discussion here, people might be interested in this
little item which cropped up today in the GPS newsgroup:

In article <38E10809.77B714BA@mitre.org>, Michael J. White
<mwhite@mitre.org> wrote: 

>> I know where Meter and Nautical mile came from.  But can anyone tell what
 >> the statue mile is?  I am a "metric" person :) 
> >One statute mile is equal to 1.60934 kilometers.

A kilometer is 1000 meters.  A statue mile derives from a Roman mile
(which has the same word basis as the metric prefix `"milli'' but with
the same meaning as the metric prefix ``kilo''), which is 1000 Roman
army standard paces.  In turn, a Roman army standard pace was about 5
and 1 quarter feet (1.609344 meters from the statue mile definition
^^^^^^^^                              +--- Yes, this is nit-picking.
in the USA).

As I noted earlier, a Roman pace is the distance between consecutive
contacts with the ground of the left foot (the reason that military
marching steps off with the left foot).

On a related (by the connection to Roman times) note:

[The following clipped from another source]

Space Shuttle, Horse's Ass...

The US standard railroad gauge (width between the two 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 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 have that particular odd wheel spacing? Well,
if they tried to use any other spacing, the wagon wheels would break
on some of the old, long distance roads in England, because that's the
spacing of the wheel ruts.

So who built those old rutted roads? The first long distance roads in
Europe (and England) were built by Imperial Rome for their legions.
The roads have been used ever since.

And the ruts in the roads? Roman war chariots first 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 were all alike in the matter of wheel spacing. The United States
standard railroad gauge of 4 feet, 8.5 inches derives from the
original specification for an 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 war chariots were made
just wide enough to accommodate the back ends of two war horses. Thus,
we have the answer to the original question.

Now the twist to the story..............

There's an interesting extension to the story about railroad gauges
and horses' behinds. When we see a Space Shuttle sitting on its launch
pad, there are two big booster rockets attached to the sides of the
main fuel tank. These are solid rocket boosters, or SRBs. The SRBs are
made by Thiokol at their factory in Utah. The engineers who designed
the SRBs might have preferred 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 had to run through a tunnel in the
mountains. The SRBs had to fit through that  tunnel. The tunnel is
slightly wider than the railroad track, and the railroad track is
about as wide as two horses' behinds. So, the major design feature of
what is arguably the world's most advanced transportation system was
determined over two thousand years ago by the width of a Horse's Ass!

Randolph J. Herber, herber@dcdrjh.fnal.gov, +1 630 840 2966, CD/CDFTF
PK-149F, Mail Stop 318, Fermilab, Kirk & Pine Rds., PO Box 500,
Batavia, IL 60510-0500, USA.  (Speaking for myself and not for US, US
DOE, FNAL nor URA.)  (Product, trade, or service marks herein belong
to their respective owners.)