Everyone knows the horse's-rear-end story. Rome did not do it.
The meme goes like this: the width of American railroad tracks descends from Roman war chariots, two horses wide, which carved the ruts that became the roads that set the gauge that constrained the Space Shuttle's booster rockets. A major design feature of the world's most advanced transportation system, determined two thousand years ago by the width of a horse's backside.
It is a perfect story. It is also wrong about Rome.
The ruts at Pompeii vary by two feet. Roman vehicles were never standardized across the empire. Chariots were light racing machines, not the heavy freight wagons that actually carved road surfaces. The chariot-to-booster chain, satisfying as it is, has no links that hold.
George Stephenson built the Stockton and Darlington Railway in 1825 and used the gauge of the local coal-mining wagonways he already knew. That gauge won not because it was optimal but because his locomotives were commercially successful first. Isambard Kingdom Brunel built a competing railway to a mathematically superior seven-foot gauge and lost. The standard that won was the standard that networked first.
Here is what is actually true about the Space Shuttle: the solid rocket boosters were manufactured in Utah and had to travel by rail to Florida. The tunnels between the factory and the launchpad set their maximum diameter at 146 inches. The most advanced propulsion system of the twentieth century was constrained by nineteenth-century railroad infrastructure.
Rome did not cause it. But the lesson Rome would recognize is this: the standard you ship today is the tunnel someone's rocket must fit through in a century.
That is the operating system this newsletter exists to install. Not philosophy to contemplate. A set of measurements to build against, before the rocket is designed.
The gauge meme gets Rome wrong. The principle it was trying to illustrate is the most Roman idea there is. Standards outlive their authors, their logic, and everyone who thought they were building something temporary.
Build deliberately. Everything you ship is permanent until someone pays the switching cost to change it.
Next week: the 1920s telephone switchboard standard that is currently housing the hardware running artificial intelligence.