10 
BULLETIN 661, IT. S. DEPARTMENT OF AGRICULTURE. 
trucks to hold the trays, and the curd mill. Several creameries may 
combine to maintain a central drying plant and ship their green 
curd to the plant for drying; this is advisable if each plant, because 
of the small quantity of curd handled, can not afford a complete 
equipment. 
TUNNEL DRIER. 
The best type of drier is made of tongue-and-groove boards nailed 
both sides of the studding, the space between being filled preferably 
Fig. 2. — Well-constructed double-tunnel drier lined with galvanized iron. Two large 
pipes take off the heated air after it has passed over the casein. Steam radiator for 
heating the air shown at top and farther end of tunnel. 
with dry sawdust or other insulating material. It is advisable to 
line the tunnels with galvanized iron if they are to be used continu- 
ously, as the large volume of heated air passing through them dries 
the boards out to a considerable extent. A cheaper type of construc- 
tion consists in nailing tongue-and-groove boards on only one side 
of the studding. While, because of leaks and other losses, that kind 
of drier is not so economical of the heated air, it gives satisfactory 
results. It is more economical of both space and construction to 
have a double-tunnel drier built along the wall where it will be least 
in the way. The tunnel should be made one inch wider than the 
trucks and drying trays, to allow sufficient room for moving the 
