tobacco temperature and moisture. The top of the hogshead on the upper tier coincided 

 with the 16- foot elevation used to monitor conditions inside the warehouse. The hogs- 

 heads monitored were prized in October with 1966- crop tobacco, type 11-A, grade B4F, 



In each of the four selected hogsheads, tobacco temperature was monitored at 4-, 

 12-, and 20- inch depths. Copper- constantan thermocouples were used to detect temper- 

 ature, and readout was made with a 24-point transistorized recorder. The recorder 

 was automatically activated daily at noon for about 6 minutes. Measurements were 

 accurate to within ±0.5°F. 



Tobacco moisture was monitored with dial- stem hygrometers having animal mem- 

 brane as the moisture detector. Moisture was monitored in each of the four hogsheads 

 at depths of 4 and 12 inches. The hygrometers remained in the tobacco continuously, 

 but readings were made only weekly. Moisture accuracy was within ±0.5 percent calcu- 

 lated on a wet basis. 



All instruments were checked for calibration at 4- week intervals. At each cali- 

 bration, the hygrometers were rejuvenated with moisture. The field instruments were 

 calibrated to an electric hygrometer indicator using sensors of bifilar windings of 

 palladium hygroscopically coated with lithium chloride. 



RESULTS 



The data have been condensed into tabular and graphic form for presentation. De- 

 tailed data are available for inspection at the Tobacco Insects Investigations Laboratory, 

 Richmond, Va. 



Figures 2-4 show the outside temperature range and the related mean warehouse 

 temperature data. During the year, the mean warehouse temperature in a reduced 

 fluctuating pattern followed closely the higher temperatures recorded outside the 

 building. In the warehouse, the maximum temperature at the 16- foot elevation was 

 usually several degrees higher than at 2 feet above floor level (table 1). With few ex- 

 ceptions, temperature recorded at the 8- foot elevation was near the average of tempera- 

 tures at 2 and 16 feet. The minimum daily temperature monitored at the three stations 

 was consistently within a range of 3°F. This indicates that daily, after sunset or when 

 there was a cloud cover, the warehouse temperature approached uniformity at the 

 monitoring stations. 



Temperature difference in tobacco among the four vertically stacked hogsheads 

 was minimal. Temperature in the top hogshead was usually slightly higher than the 

 next- in- line unit. Tobacco temperatures at 12- and 20- inch depths in the top and 

 bottom hogsheads generally did not vary more than 2°F. At the 4-inch depth, the 

 temperature variation rarely exceeded 4°F. Fluctuation of tobacco temperature within 

 any hogshead was greatest at the 4- inch depth in the top hogshead. (Figures 5-16 show 

 these data.) 



6 



