HARVESTING AND MARKETING 175 



the southern states they are less satisfactory, and in 

 any case they are unreliable when mismanaged. 



The two important things to be looked after in 

 building these houses for common storage are (i) in- 

 sulation, and (2) ventilation. 



Insulation is provided as described above by mak- 

 ing very tight walls with dead air spaces. Formerly 

 it was recommended to fill the spaces with sawdust or 

 some similar material. This is now known to be in- 

 advisable. 



Ventilation should be secured by having a reason- 

 able number of windows which may be easily opened 

 and shut. These should be near the floor or else spe- 

 cial ventilators should be provided at the floor level, 

 opening on all sides of the building. An adequate dis- 

 charge for warm air must also be provided from the 

 upper part of the storage room. This is usually se- 

 cured by ventilating shafts running from the storage 

 room to the roof. A circulation of air can be secured 

 at critical times with this construction by lighting a 

 lamp and placing it on a small shelf in the ventilating 

 shaft. The windows of such storage houses are 

 opened at night when the temperature is low and are 

 closed early in the morning before the thermometer 

 goes up. In this way a storage house can be thor- 

 oughly cooled off and can be held at a very uniform 

 temperature when once it is cooled. Of course the 

 cooling is not so positive as with artificial refrigera- 

 tion, nor can it be so quickly accomplished. 



The construction of cold storage houses with arti- 

 ficial refrigeration is rather a complicated matter, 

 which even the refrigeration engineers do not under- 

 stand any too well. It would be going too far to take 



