Palisade Tunnel, 94 Pennsylvania Railroad Shield, 270 Percussion Drills, 24 Pilot Method of Tunneling, 192 Plank Centers, 69 Platform Cars, 59 Plenum Method of Ventilation, 329 Pneumatic Caissons, 287 Polar Protractor, 39 Portals, 81 Power Drills, 24 Power Plants: Air Compressors, 87 Canals and Pipe Lines, 86 Cascade Tunnel, 98 Croton Aqueduct Tunnel, 95 General Description, 84 Graveholz Tunnel, 98 Hoosac Tunnel, 93 Hudson River Tunnel Pennsylvania Railroad, 279 Mont Cenis Tunnel, 92 Murray Hill Tunnel, 128 Niagara Falls Power Tunnel, 97 Palisades Tunnel, 94 Receivers, 89 Reservoirs, 86 Simplon Tunnel, 117 Sonnstein Tunnel, 99 St. Clair River Tunnel, 99 St. Gothard Tunnel, 133 Steam, 85 Strickler Tunnel, 96 Turbines, 86 Prelini’s Shield, 251 Presence of Water, 7 Prevention of Collapse, 303 Progress in Sinking Shafts, 343 Progress of Excavation, 342 Progress of the Work, 342 Progress in Simplon Tunnel, 122 Quantity of Air for Ventilation, 331 Quicksand Tunneling: General Discussion, 188 Removing the Seepage Water, 191 Quantity of Timber in Strutting, 54 Receivers, 89 Relining Tunnels, 315 Boulder Tunnel, 315 Little Tom Tunnel, 321 Mullan Tunnel, 319 Repairing of Accidents in Tunnels, 308 Reservoirs, 86 Roof Arch Lining, 77 Roof Shield for Boston Subway, 251 Roof of Caissons, 287-291 Rotary Drills, 27 Ryder, B. H., 296