DISCUSSION. SUBAQUEOUS TUNNELLING.

Keywords: SUBAQUEOUS, UNDERWATER, TUNNELS, RAILWAYS, SHIELDS, BENDS, COMPRESSED, AIR, PURIFICATION, DISEASES, CARBONIC, ACID, TUNNELLING, BRIDGES, CAISSONS, SINKING, GRAVEL, SHUTTERS, SKIN, FRICTION, SETTING OUT, SURVEYS, UNDERGROUND, SICKNESS, ILLNESS, HEALTH, WORKERS, BAKERLOO LINE, BALLAST, CONSTRUCTION, SHAFTS, THAMES, ENGLAND, GREENWICH, ROTHERHITHE, FORTH, BLACKWALL, BAKER STREET, WATERLOO, BAKERLOO LINE, LONDON, UK