HANDLING LETTUCE AND CELEEY. 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 all 



