1904.] DUDLEY — PASSENGER CAR VENTILATION. 247 



Niakomak, Greenland. Found 1819. (i gr., VI.) 



Sao Francisco, Brazil. Found 1874. (479 gr., V; 26 gr., 

 VI.) 



Nikolojewskaja Wosimskaja, Russia. Found 1883. 87 gr. 

 8 cm. 



A rtificial Products . 



Glowed Steel, (i gr., VI.) 



Devitrified molten Pitchstone. (VI.) 



IX. Duplicates for Exchanges. 



In a synoptical collection the duplicates destinated for 

 exchanges should be registered separated from the pieces of 

 the main collection by three reasons: to avoid the constant 

 moving of weights in the catalogue, to avoid parting with 

 specimens, which show important peculiarities and to enable 

 directors or owners of other collections to arrange proposi- 

 tions for exchange. 



As the present article has a more theoretical scope, dupli- 

 cates were not registered at all; they form a series of 90 

 localities in the weight of together 85 kilograms. 



A SYSTEM OF PASSENGER CAR VENTILATION. 



BY CHAS. B. DUDLEY, PH.D., 



CHEMIST, PENNSYLVANIA RAILROAD COMPANY. 



{Bead April 8, 190 4.) 



The ventilation of passenger cars is no small problem. The 

 ordinary passenger coach includes about 4,000 cubic feet of space, 

 and the difficulties of the problem will be apparent when it is stated 

 that it is proposed to take into this limited space sixty people, to 

 keep them in that space for from four to six hours at a time, to keep 

 them warm enough for their comfort in winter, to supply them 

 with the necessary amount of fresh air, and at the same time to, 

 as far as possible, exclude objectionable material from without, 

 such as smoke and cinders. It is perhaps not strange, in view of 

 the small space and large number of people and the inclemency of 

 the weather, that progress in the solution of the problem has been 

 slow. It is believed that the system which will be described is a 

 decided step forward in this matter, and while it niay not be the 



