HANDLIXG LETTUCE AXD CELERY. 5 
plant consists of a complete 12-ton refrigerating outfit installed in a 
freight car. Ammonia expansion coils in a well-insulated compart- 
ment at one end of the car furnished as low a temperature as was 
desired ; and a 45-inch fan forced the necessary circulation of air. 
Refrigerator cars were loaded with lettuce in the usual manner and 
brought to the precooling plant, where cold air was then blown 
through the car, entering at one of the bunkers and going out at the 
other. Twelve electrical thermometers were distributed through the 
load. One thermometer was placed in the lettuce near the outside 
of the head end of the package and one in the center in each of six 
Fig. 3.— Hampers of lettuce loaded in a refrigerator car with very little space between the hampers for 
circulation of air. 
hampers, which were located as follows : Two hampers at each end of 
the car, next to the bunkers, placed midway between the side walls, 
one at the top and one at the bottom of the load. The other two 
hampers were located as near the center of the car as possible, one 
at the top and one at the bottom of the load. The thermometers 
were connected with a main cable, which extended through the side 
ventilators to the outside of. the car and provided a means of accu- 
rately determining the temperature at any time without opening the 
doors. The precooling was commenced as soon as possible after the 
cars were loaded and continued until the average temperature of ^11 
