414 Bureau of Farmers' Institutes. 



The temperature and moisture in each room can be controlled 

 independently of the other rooms. It is possible to get a range 

 of temperature varying from below 40° F. to 90° F. in any room. 

 Each room is provided with a hot-air flue from below, and a cold- 

 air flue from above leading from the chamber in the attic which 

 contains ammonia expansion coils and brine tanks. These two 

 flues, one for cold and one for hot air, are closed by dampers and 

 these dampers are operated by means of compressed air tubes con- 

 trolled by thermostats. There is also a ventilating fine in the 

 ceiling of each room. The thermostat is set so as to register a 

 definite temperature in each room. For example, in one room 

 it is set at 70° F. ; when the temperature falls one degree below 

 70° F., the thermostat is affected in such a manner that it turns 

 a valve and this causes the compressed air to open the hot-air 

 damper in the floor. On the other hand, when the temperature 

 rises to 71° F., the cold-air flue in the ceiling is opened. Thus 

 we have an alternate admission of hot air and cold air, causing the 

 temperature to rise or fall above or below the given point at which 

 it is desired to hold the room. So delicate is the operation of this 

 system that merely breathing upon the thermostat will open the 

 cold-air flue, while fanning the thermostat will open the hot-air 

 damper. We are therefore able by this system to hold tempera- 

 ture within a verv limited range. Under most favorable condi- 

 tions limit of variation is only two degrees. Even with a much 

 wider variation the temperature of the interior of a cheese would 

 not be affected to the extent of more than a small fraction of a 

 degree, as we have shown by placing a thermometer inside a cheese 

 and keeping it there for some weeks. 



It would be impossible, even with the help of drawings, to give 

 a completely intelligible description of our arrangement for con- 

 trolling temperature. The system itself must be seen in operation. 



It is more difficult to control moisture than temperature, and 

 hold it within narrow limits. The most practicable and efficient 

 method we have found is to make use of yard-wide pieces of coarse 

 felt having strong capillary power. One end of the felt clips into 

 a trough of water situated near the top of the room, and the lower 

 end drops in a trough placed on the floor. The water is sucked 

 in by the felt at the upper end and gradually distributes itself 

 throughout the whole piece, the excess of water dripping into the 

 lower trough. It is necessary to boil the cloths occasionally in 

 water slightly acidulated with some acid, like acetic or hydro- 



