A HORSE'S ASS


As a fast typist, I often wish my thoughts could move as rapidly as my fingers.  Yet staring down at the keys, fingertips poised for the next idea, I know that my speed is in spite of the design the board, not because of it.  I have had so much practice that I am able to overcome the bizarre QWERTY layout, as all typists must.
This is a problem of legacy.
In families it can be desirable; in designs it can be stifling.  Design legacy refers to factors in the process of making a thing that come from historical precedent, the decisions of the sometimes dim past.  These can be beneficial and make sense when the design has the proper fit from the start.  The shape and structure of the violin, for example, has not changed that much since its consolidation in the 16th century.  But sometimes the legacy is simply an artifact of the story, a remnant that made sense once but now lingers on as a vague limitation.  The QWERTY keyboard is a good example of this.  Perhaps this layout separated the keys in a way that would avoid mechanical chaos back when the device used levers, but it is now simply a relic that we live with.

Our design choices are often determined by a history that may or may not be clear to us or even make sense, a history that sets the parameters of our vision, whether we are aware of it or not.  Consider, for example, the fact that the distance between the rails of all trains in the United States is precisely four feet eight and one half inches.  This is called the Standard Railroad Gauge and any industrial designer who was not familiar with it would be asking for train trouble.  It is an odd fact but an unavoidable rule.
Where on earth did they come up with such a specific measurement?

The easy answer is that US trains were built based on English trains because our railroads were designed by English expatriates and that was the width used in England.  But then why did the Brits use that number?
The answer to that question is that the first rail lines in England were built by the same people who built the pre-railroad tramways and that is the precise gauge those folks used as well. And why was that gauge width used for the tramways?  Because the people who built the tramways used the same equipment, tools, and measuring devices used for building the wagons that came before the tramways.  And – you guessed it – the wagon wheel spacing was based on that precise width.
The next step backwards should be obvious by now.  The wagon builders relied on the spacing of the well-worn ruts of the old roads in England at the time; any other wheel spacing would have damaged the wagons. Which inevitably brings us to why those old ruts came to be four feet eight and one half inches wide.

Imperial Rome built the first long distance roads in Europe and England for their great marching armies.  The ruts were formed by the Roman war chariots and any other vehicles, then and since, had to match the ruts or risk destroying their own wheels.  All Roman chariots, naturally, had the same standard wheel spacing of four feet and eight and a half inches.
Which leaves one final unavoidable question about the width of those original chariots and the reason the measurement ever came about in the very first place.

The answer?
Chariots were built with that wheel width because that exact measurement was just wide enough to accommodate the rear ends of two standard Roman warhorses.
So there is no other way to say it.  A basic decision that has influenced all train design for the past two millennia comes down to a horse’s ass.
I wonder how many other decisions do too.

No comments:

Post a Comment