The Invention of the Fire Escape

The iron stair bolted to the front of an old apartment block is usually read as a piece of engineering. It is better read as a piece of law. Tall residential buildings existed for decades before anything was attached to them, and what changed was not the availability of iron but the appearance of a rule that a landlord could be prosecuted for ignoring.

The early rules were vague in a way that shaped the result. Several cities required a means of escape without saying what one was, and landlords answered with rope ladders, knotted rope, and iron rungs set into the brickwork. These satisfied the letter of the law and were useless to most of the people living there, since using them required strength, daylight and an absence of panic. Only after a series of well-reported disasters did the rules begin to specify a stair, a width, and a route that ended at the ground.

The lesson has outlived the ironwork. A requirement written as an outcome, such as providing for escape, will be met by whatever is cheapest to install, and the cheapest option is usually the one that has never been tested by a frightened person at night. A requirement written as a specification is clumsier and ages badly, but it can be inspected from the street.