See the Space Shuttle on its launch pad,

Two booster rockets it’s always had,

Solid Rocket Boosters made in Utah factory,

Thiokol Corporation’s boost into history.

Now, design engineers for SRBs

A little fatter may have wanted these,

But they have to be shipped via rail,

To launch site, and therein lies a tale.

The rail line runs through a tunnel,

Through hole in mountain must funnel

That’s slightly wider than the track

Of a standard gauge from way back.

So the distance between parallel rails:

Four feet, eight point five inches, the details.

That is an exceedingly odd number,

So how did the standard it encumber?

Well, that’s what the English, we’re told,

Used for their rails in Merry Olde.

English expatriates filled engineers’ ranks

In the new country, so to them, our thanks.

But why did the English do it that way?

Well, people who built the pre-rail tramway

Built the first rail lines and used that gauge,

Their jigs and tools to easily assuage.

So why did tramway folk use that gauge?

They built wagons before the tram rage,

Again, jigs and tools they’d daily face,

And their wagons had the same wheel space.

So why did wagon wheels get that gauge?

Because other spacing caused breakage

On some of the old, long-distance roads,

With ruts of that width, from hauling loads.

So who built the rutted roads in Merry Olde?

None other than Imperial Romans rolled--

War chariots driven by their legions,

Pressed ruts into trails connecting regions.

These paths, once established, were roads

That all used for transporting loads.

Roman chariots all designed with same cut,

Shippers copied the Romans, used the same rut. 

How did Romans determine spacing of wheel?

They examined their world, what to them was real,  

Measured two horses pulling side by side,

Added space to jostle, and that’s how wide

Roman war chariot wheels were spaced:

Two horses wide with room to be raced.

Two thousand years since they would derive

The odd number: four feet, eight point five.

So the most advanced transport in the world,

Limited by Romans, as just unfurled,

Calculated: one horse’s ass times two,

As fuzzy a measure as we can do.