WPneumaticsWAtmospheric railwayWBeach Pneumatic TransitWCash carrierWCompressed air gramophoneWCrystal Palace pneumatic railwayWDalkey Atmospheric RailwayWGladhand connectorWLamson Engineering Company LtdWLondon Pneumatic Despatch CompanyWMekarski systemWParis pneumatic postWPlayer pianoWPneumatic cylinderWPneumatic tubeWPneumatic tube mail in New York CityWPrague pneumatic postWPressure regulatorWRohrpost in BerlinWWaterloo and Whitehall Railway
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W