I was glad to see the link to the Taylor Air Compressor. I had never seen that before, so I downloaded it to study the details. The idea of using river hydro power to compress air suggests a water wheel or turbine to power a reciprocating air compressor. But this ingenious Taylor compressor has no moving parts.
Regarding subject matter here, I assumed the original post was asking about the Hecla & Torch Lake RR which we had previously discussed in the 2011 thread. That was a private mining railroad.