go PRESERVATION OF FOOD BY REFRIGERATION ; 
3rd. The flow of heated air upwards towards the outlets 
being baffled by the descending cold currents, and the air 
being incapable of being heated by radiation, there is no 
absorption, and very little heating by contact. We thus 
have the apparent anomaly of an intensely cold air, and 
bodies of meat retaining their heat long enough for decom- 
position to set in. To those unacquainted with the 
properties of air and radiant heat, such a state of affairs 
would seem impossible, and all sorts of theories are invented 
to account for what is a perfectly natural phenomenon, if 
properly understood. 
In conclusion, as an example of the serious loss that can 
arise through the want of accurate information, I would 
draw your attention to the construction of the Brisbane 
Freezing Rooms at present under erection. Here we find 
brick walls, with a space filled with cow hair, and a cement 
floor. Referring to the table (No. 7) of the conducting 
powers of the different substances used in buildings, and 
calculating the flow of heat through the walls, it will be 
found that the loss under the same conditions as those 
given in the previous calculations would be 2.03 units per 
square foot per hour, and through the floor 4°13 units per 
square foot per hour, as compared with 0.85 units through 
the ceiling, which is composed of wood and cow-hair and 
sawdust insulation. Had the insulation been made of 
wood and charcoal, inside a g inch brick wall, and the floor 
covered with lead or zinc, to prevent damp, a very con- 
siderable saving of engine power would result. 
