Water columns

gcp13

They don't make them like they used to. The one on the right has two floats one for high water and low-water and uses its own steam to https://us.v-cdn.net/5021738/uploads/editor/gc/yqdr01wfjmew.jpg
blow off a whistle if the float is activated.
It also has a large reservoir for sediment

JStar

And when the whistling becomes too annoying, you just invent a water-column without it.

gcp13

Can't imagine having to clean it or keeping the floats clean
You can tell these devices were ment to have boiler fireman on constant watch