New York Agkicultural Experiment Station. 197 



dampers, and these dampers are operated by means of com- 

 pressed air tubes controlled by metallic thermostats. There is 

 also a ventilating flue in the ceiling of each room. The 

 thermostat is fixed so as to register some definite temperature 

 in each room. For example, in one room the thermostat is set 

 at 70° F. When the temperature falls one degree below 70° F., 

 the thermostat is affected in such a manner that a valve is 

 turned and this causes compressed air to close the cold-air 

 damper in the ceiling and to open the hot-air damper in the 

 floor, thus restoring the temperature to 70° F. On the other 

 hand, when the temperature rises to 71° F., the cold-air flue in 

 the ceiling is opened and the hot-air flue is closed, when the 

 temperature soon begins to drop. Thus we have an alternate 

 admission and exclusion of hot air and cold air, causing the 

 temperature to rise a little above or fall slightly below the 

 given point at which it is desired to hold the temperature of 

 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 able, therefore, by this system to hold temperature within 

 a very limited range. Under most favorable conditions, the 

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

 temporary 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 under observation for several 

 weeks. 



CONTROL OP MOISTURE), 



It is more difficult to control moisture than temperature, so 

 as to hold it within narrow limits. The most practicable and 

 efficient method we have found adapted to our conditions is to 

 make use of yard-wide pieces of coarse felt, having a strong 

 capillary power. One end of the felt dips in a trough of water 

 situated near the top of the room and the lower end drops into 

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

 felt at the upper end and gradually distributes itself throughout 



