Roman aqueducts

Brief contrast — pre-beam-theory construction relied on safety factors of five-to-ten because brittle materials (stone, brick) could not be sized to calculation. Roman aqueducts cited as the canonical example of this oversized-for-safety regime. ## Figures referenced (not cases)

What they knew from the 1850s, 60s, and 70s is, you could measure the force of fracture of a bar of steel, and that would allow you to calculate — because they had developed beam theory — how strong something would be. That way you could size the parts, rather than just making things ten times larger than they needed to be, which is what they did out of stone and brick — the cathedrals and the Roman aqueducts. They actually could calculate to use the least amount of material. They still had safety factors of five and ten because cast iron was sort of brittle, and they knew that.

Concrete water conveyance — the long-duration historical anchor in the pipe-material progression: trough → wood → stone → concrete (Roman) → lead → galvanized → copper → plastic.

Conveying water over the ages — what was the first material people used to convey water? They may have had to go down to the stream, and if they had a bucket made out of clay, a clay pot — or maybe they just scooped it up with their cupped hand. But after that, if they wanted to convey it, what might they have done? They could have used animal skins. I was actually thinking of soil. They might dig a hole and make a trough — except it leaks through. So what did they use next? They probably would have lined it with wood, because they had lots of wood, it was easy to work. After that they might use stone, then concrete. The Roman aqueducts were concrete. Then in the 18th and 19th centuries they were using lead pipe.