In rec.woodworking, Scott Lurndal wrote:
Leon lcb11211@swbelldotnet writes:
I do believe the valve is low but IIRC not below where it couples to the
main. That union is above ground and in some cases a few feet above
ground on the old ones, subsidence.
https://gizmodo.com/why-fire-hydrant...ter-1619974872

That was in interesting read. It also answers a question I never cared
enough to search for an answer: why are fire hydrants sometimes called
"fire plugs"?

In a "this is rec.woodworking" vein, I'm now wondering how the logs were
hollowed out to make the wooden water mains. Drilling a hole lengthwise
through a log seems tricky enough with modern tools. Doing it in large
quantities before steam engines must have involved some interesting
techniques.

And more "Bonus Facts:" those fire cisterns mentioned as a "colonial"
water store for fire fighting? Still exist in San Francisco. SF has two
independent water systems. One is household and fire hydrants, one is
fire hydrant only, for backup. The two have different styles of
hydrants. Sometimes you'll see hydrants for each system next to each
other.

Better pictures:
https://www.amusingplanet.com/2021/0...-cisterns.html

More official:
https://sf-fire.org/water-supply-systems

Elijah
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joining a collection of logs into a water main must have also been tricky