Re: [SI-LIST] :PCB Bd thkness'

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From: Kim Helliwell (khelliwe@acuson.com)
Date: Wed Mar 08 2000 - 08:48:41 PST


David Instone wrote:
>
> OK I can resist no longer! see below
> Killoy Richard-P29744 wrote:
> ...snip....
> > 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.
> ...snip...
> > 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.
> An interesting theory, but The early wagon ways were simply wooden
> boards laid end to end in two lines. When these were pulled by a rope
> from a stationary engine at one enf of a line. they had to do something
> to stop the wagons coming off. So they put vertical boards on the
> OUTSIDE edges of the running boards. The distance between these boards?
> 5 feet, a nice round number. Now when they came to put in switches it
> doesn't work if the rails are flanged so they flanged the wheels on the
> inside and keeping the same wheel spacing and a tad for running
> clearance gives you 4 ft 8.5 inches over the flanges.
>
> Going back to the first point, if Brunel had had his way we would have
> had 7 ft spacing. The Great Western (of England) built their lines on
> this rail gauge.

I also liked the story and have seen it more than once. It's a nice
story, but probably untrue, as you point out, David.

Also, one of the few facts I remember from 8th grade American history
is the difficulties caused by differing railroad gauges used by the
various rail companies that were operating in the mid 1800's. Rail
gauges were many and varied. While it's possible that the one that
survived owed something to Roman chariots, I wouldn't bet that way.

Puts me in mind of the saying about the beautiful theory, that's
"neat, plausible, and wrong." (anyone know who said this and what
the full quote is, by the way?)

-- 
Kim Helliwell
Senior CAE Engineer
Acuson Corporation
Phone: 650 694 5030  FAX: 650 943 7260

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