[I didn't write this. It's from another anonymous joke email. Sounds plausible.]

Does the statement, "We've always done it that way" ring any bells...? The US standard railroad gauge (distance between the rails) is 4 feet, 8.5", an exceedingly odd number.

Why was that gauge used? Because that's the way they built them in
England, and English expatriates built the US Railroads. And, why did the English build them like that? Because, the 1st R.R. lines were built by the people who built the pre-R.R. tramways..that's the gauge
they used. And, why did "they" use that gauge then? Because, the people who built tramways used same jigs and tools used in building wagons, which used that wheel spacing.

Okay! But, why did wagons have that odd wheel spacing? Because, if they tried to use any other spacing, the wagon wheels would break on some of the old, long distance English roads, as that's the spacing of the wheel ruts.

So, who built those old rutted roads? That would be Imperial Rome...1st long distance roads in Europe (and England), for their legions. The roads have been used ever since.

And why the ruts in the roads? Because, Roman war chariots formed the
initial ruts, which everyone else had to match for fear of destroying their wagon wheels. Chariots were made for Imperial Rome, and were all alike in the matter of wheel spacing.

The US Standard RR Gauge, 4' 8.5", therefore, is derived from the original specs for an Imperial Roman war chariot. And bureaucracies live forever.

So the next time you are handed a spec and told, 'we have always done it that way', and wonder what horse's ass came up with that, you may be exactly right! Imperial Roman war chariots were made just wide enough to
accommodate the back ends of 2 war horses.

Now, here's where it gets interesting, particularly for you Aerospace
Engineers out there ...

When you see a Space Shuttle sitting on its launch pad, there are 2 big booster rockets attached to the sides of the main fuel tank... solid rocket boosters, or SRBs... SRBs made by Thiokol at their Utah factory. The engineers who designed the SRBs would have preferred to make them a bit "fatter," but the SRBs had to be shipped by train from factory to launch site. The RR line that runs from the factory happens to run through a mountain tunnel. The SRBs had to fit through that tunnel. The tunnel is slightly wider than the RR track, and the RR track, remember, is about as wide as 2 horses' behinds. So, a major Space Shuttle design feature of the world's most advanced transportation system was determined over 2,000 yrs ago by the width of a horse's ass.

And you thought being a horse's ass wasn't important!!!