No mention of drying the air in the network. They had to have good driers to prevent water from entering the network or elaborate number of venting points to remove water from the low points of the network. Anyone know more?
I'm no expert on this, but could this be the reason of the confusion in the picture titled "Section of the Quai de Gare usine: 1892", where the author mentions "A = drying channels (not sure what that means- they look like sewers in cross-section. May just mean 'drainage')"?
Routing it all underground is going to do a really good job drying it at the expense of tons of condensation in the lines. The latter is easily solved with drain valves and traps like you'd find in a steam system.