oct. — mar. 1859-60.] Rooms in Tropical Climates. 



327 



Cor. 3. If what has been said in the early part of the paper of 

 the difference between air, cool merely to the feelings, and that 

 which is cold to the thermometer be true, i. e that the former being 

 really high in temperature, and merely feeling cool to the skin by 

 being agitated by a fan, or mixed with watery vapour, is rarefied to 

 the full amount of its real temperature ; and so forms a weak and 

 diluted sustenance for the lungs; while the latter being really 

 low in temperature, is dense, and gives, proportionately, concen. 

 trated food to the breathing organs ; if this be true, which it cannot 

 but be, then it follows, that air mechanically compressed, and 

 breathed in that state, may be very beneficial in many cases of 

 disease, when the lungs may be very small, or may in part be 

 destroyed by consumption or other malady; for by continued com- 

 pression, as much oxygen may be contained in a cubic inch of the 

 compressed air, as in a hundred of the ordinary pressure and tem- 

 perature of the atmosphere. To carry out the principle in such a 

 manner as to be adapted to all cases of temperature and pressure 

 it would be necessary to have a small air-tight room, made proba- 

 bly of iron, connected at one end with the pipe coming from the 

 escape-valve of the cooling room, and having a similar valve at 

 the other end. The reason of not making the pump force the air 

 at once into the room, is, that the temperature would thereby be 

 too much raised; but by having a greater compression in the worm 

 cooler than in the room, the latter may be supplied with air of any 

 desired temperature and pressure ; and Mr. Petrie's table, given 

 above, will show exactly the pressure to which the two escape-valves 

 should be set, for any particular case. 



