PRIZES FOR THE INVENTOR 



145 



covered with salt. This was placed in 

 another room at a higher elevation than 

 the tank, and a pipe covered with asbestos 

 paper was employed to lead the cold air 

 into the tank. 



The first effect was the drying of the 

 walls, and then I felt the level of the cold 

 air gradually rising. At last it came over 

 my head. The tank was full, and I 

 found myself immersed in cool air. I 

 felt so cool and comfortable that it 

 seemed difficult to believe that Washing- 

 ton stood sizzling outside. I climbed up 

 the ladder in the swimming tank until my 

 head was above the surface, and then 

 found myself breathing a hot, damp, 

 muggy atmosphere. I therefore speedily 

 retreated into the tank, where I was per- 

 fectly cool and comfortable. 



Guided by this experience, I tried an- 

 other experiment in my house. I put the 

 refrigerator in the attic and led the cold 

 air downward through a pipe covered 

 with asbestos into one of the rooms of 

 the house. The doors were kept shut and 

 the windows were opened at the top. 

 The temperature in that room was per- 

 fectly comfortable, about 65 degrees. 



At that time the papers were speaking 

 of some ice plant that had been installed 

 in the White House and congratulated 

 the President upon a temperature of only 

 80 degrees when the thermometer showed 

 100 degrees outside. At this very time I 

 enjoyed in my house a temperature of 65 

 degrees (the ideal temperature), with a 

 delicious feeling of freshness in the air. 

 Even when the air had risen to the same 

 temperature as the rest of the house, as 

 measured by a thermometer, the room 

 still felt cool, because the air was drier, 

 thus promoting perspiration that cooled 

 the skin. 



SELLING COLD AIR IN PARIS 



In this connection I may say that there 

 is a very interesting cooling plant in 

 Paris, France, run by the Societe de l'Air 

 Comprime. Very many of the cafes and 

 restaurants in Paris have cold rooms for 

 the storage of perishable provisions, and 

 these rooms are cooled by compressed air 

 supplied by this company. 



The plant consists of large pipes laid 

 down under the streets of Paris, with 



small branch pipes leading into the cafes 

 and restaurants. At a central station 

 steam-engines pump air into the pipes and 

 keep up a continuous pressure of from 

 four to five atmospheres. As there are 

 several hundred kilometers of these pipes 

 under the streets of Paris, they form a 

 huge reservoir of compressed air at the 

 ground temperature. 



In the cooling room of a cafe they 

 simply turn a little cock and admit the 

 compressed air into the room. A gas 

 meter measures the amount of air ad- 

 mitted and charges are made accordingly. 



The compressed air, by its expansion, 

 produces great cold, and the cooling effect 

 is still further increased by allowing the 

 air to do work during the process of ex- 

 pansion. Dumb-waiters, elevators, and 

 even sewing-machines are thus run very 

 economically in connection with the sys- 

 tem by means of compressed-air engines. 



WILL OUR CITIES EL ARTIFICIALLY 

 COOLED ? 



Now, it appears to me that this process 

 might very easily be developed into a 

 plan for the cooling of a whole city. 

 You would simply have to turn a cock 

 in your room to admit the fresh air ; and 

 if you then take precautions to prevent 

 the cold air from running away by having 

 your room tight at the bottom and open 

 at the top, you could keep your room cool 

 in the hottest summer weather. 



I must confess that there is one other 

 subject upon which I would like to say a 

 few words before closing. 



One of the great evils attending our 

 civilization is the extreme congestion of 

 the population into the larger cities, and 

 one of the great problems of the future 

 is how to spread the population more 

 equally over the land. 



The congestion is caused by difficulties 

 of transportation; for, of course, it costs 

 much more to send a person to a distant 

 place than to one near at hand. 



But did you ever think of this : that it 

 also costs more to send a letter to a dis- 

 tant place than to one near at hand, and 

 yet a two-cent stamp will carry your 

 letter anywhere within the limits of the 

 United States, and even beyond. 



