Show force of compressed air the effects of air resistance art ar well known in the twelve and ano one 1 liala alf aniie imio SIm simplon plon tunnel where ai an exceptionally high amount of energy Is required for running the electric elect rit trains the tunnel which is fifteen leet feet wide and eighteen leet feet high with a sectional ahei area of two hundred and fifty square leet feet has a las ing current of I 1 cubic feet of all ah per second maintained ned by two laret blast fona auns at the brig end and two exhaust fans at cselle iselle trains botial with this current encounter less resistance si al than in ia open air up to fifteen and a half miles an hour but at al higher speeds or in ih the opposite direction the re resistance abstance is much greated than outside coasting by graviel down the seven per one thousand gradient a train even going with the current cannot exceed thirty five miles per hour on ace account i of cf the braking by the air |