Show CI 0 OP Alit I Tho The effects of ot air all resistance arc nrc well 1 shown in the undo 12 l simplon tunnel where an exceptionally high amount of energy is 18 required for running the electric electric electric elec elec- trains The Tho tunnel which Is fifteen feet wide and eighteen feet teet hl high h with witha a L sectional area of 50 square feet teet has hasa a a. ventilating current o of square feet reet of or air a second maintained by two large blast fans at tho the Brique end and two exhaust fans at hectic Icelle Trains goIng goIng go go- Ing lug with this current encounter less resistance than In open air all up to 15 miles an hour but In higher speeds orIn or orIn orIn In the opposite direction the resistance is Js much h greater than outside CoastIng Coasting Coast- Coast Ing Ine- IneL L by gravity s down the 7 to 1000 m maxi maximum mum gradient e a n train oven even though going with the current cannot exceed thirty five miles an hour on account ot of the braking by 11 the air j 1 |