1904.] 



DUDLEY — PASSENGER CAR VENTILATION. 



251 



per To,ooo of the mixture?" or in other words, if 10,000 cubic feet 

 of air contains eight cubic feet of carbonic acid, how many cubic 

 feet of air will be required to contain thirty-six cubic feet of car- 

 bonic acid on the same ratio? Reducing the proportion and it 

 appears that under the conditions assumed, 45,000 cubic feet of 

 fresh air per hour would pass through the car. In this illustration 

 the amount of air in the car to start with is ignored, since it is not 



an important element, and since results accurate to a few hundred 

 cubic feet are not essential. 



This brings us to the consideration of the ventilating system 

 which has been adopted as standard by the Pennsylvania Railroad 

 Company, and which is now in daily use on some Soo passenger 

 coaches on the lines east of Pittsburg and Erie, and on nearly 200 

 coaches on the lines west of Pittsburg and Erie. It may not be 

 amiss to say that the development of the system has taken several 

 years of study. A very large number of experiments have been 



