342 MARKET DAIRYING 
Where the source of ice is at too great a distance from 
the dairy, an artificial pond should be made upon ground 
with a reasonably impervious subsoil and with a natural 
concave formation. If such a piece of ground is flooded 
with water during the coldest weather, an ample supply 
of ice will be available in a very short time. 
Insulated Ice Houses. The present tendency is to 
use ice houses with insulation sufficient to dispense with 
the use of sawdust. With ice houses of this kind, the 
refrigerator is cooled by circulating the air directly over 
the ice in the ice house. See Fig. 3714, page 101. 
