I remember reading somewhere that in the days of steam traction on the Metropolitan, as an experiment overhead ducts were fitted above the track into which the funnels of the locomotives discharged. I assume that this experiment was unsuccessful, but does anyone have further information on this subject?
What you're think of were blowholes, which the District (and maybe also the Met) stationed in the crown of the arch of the "covered way" where locos used to habitually stand (eg at signals guarding junctions or at the end of platforms). There was one at Bridge St at Westminster [Bridge] station, railed off in the middle of the street. Unfortunately, horses were apt to take fright at the sudden release of steam and smoke from the condensers, and MPs get blackened when crossing the road!
Thanks stapler. I knew about the blow-holes but as well as this there was an experimental section of ducting placed above the track somewhere to carry off the smoke. It didn't work well enough to be rolled out and so consigned to oblivion. I read about it years ago and cannot for the life of me recall where!
Although not the fuller description which I have in mind, I have found the following in London's Metropolitan Railway by Alan A. Jackson p.119.
"...Sir Benjamin Baker was was commissioned to design the apparatus. He erected exhaust troughing along the top of the tunnel for a test installation attended with moderate success, but his system was rejected on grounds of high first cost and high maintenance expenditure. An alternative, designed by Christopher Anderson of Leeds, was tried out at Neasden in 1890-91, using a Metropolitan locomotive and iron plate trunking between the rails with box slides dragging along it, moved by the locomotive.* Benjamin Baker reported to the board that although the design was both good and workable it would heavily increase working and maintenance costs and was moreover very noisy. This too was therefore rejected.
"*The working of this ingenious device is described the The Engineer, 29 January 1892, pp88-90."