APPLICATION OF BEFKIGERATION TO HANDLING OF MILK. 69 
the cooler by the small rotary pump. The water is allowed to pour 
back into the tank, consequently the temperature of the volume of 
water gradually rises. During the warmest weather it was necessary 
to run the refrigerating machine from 8 to 10 hours a day in order 
to cool the water down to 35° F. and hold it at this temperature 
until used. The volume of milk handled was that from 15 cows and 
it was cooled entirely by the refrigerating water from a temperature 
of about 98° to 35° F. Had well water been used in one section of the 
cooler at least half of the refrigerating duty would have been taken off 
the machine and the time of operating the machine would have been 
reduced one half, or, for the same number of hours of operation the 
Fig. 32.— 20-cow farm milk house equipped with refrigerating machine. 
machine would have taken care of the milk of double the number of 
cows. 
The cost of electric current at the experimental farm is 6 cents per 
kilowatt-hour, and as the input to the motor is about 0.55 horse- 
power, the cost of power for operating the machine is 2\ cents per 
hour, or 20 cents for an 8-hour day. The amount of cooling water 
required is about 25 gallons an hour. 
MAINTAINING LOW TEMPERATURES DURING TRANSPORTATION. 
A great deal of the milk consumed in the cities at the present time 
is transported in wagons, or in the ordinary baggage car m use on the 
steam railroads or on the interurban electric railways, with no provi- 
sion for holding the milk at low temperatures. 
