Journal of Agricultural Research voi. xxm, no. s 
318 
Figure 13 shows the temperature changes as read from thermometers 
whose bulbs rested on top of four thicknesses of wet blotting paper in 
four different positions in a chamber which was heated by a gas flame 
below for four hours and then immediately cooled for three hours by 
means of ice and water above. The eight trays were completely covered 
with four thicknesses of folded blotters. 
The curve for position 3 on tray 1 (near three walls of the water 
jacket) represents the most rapid and that for position 1 on tray 5 (near 
the center of the chamber) very nearly the least rapid temperature 
Fig. 15.—Curves showing temperature (Changes within wet blotters when these were transferred 
two germinating chambers at fixed temperatures. 
changes occurring in any part of the chamber, the curve for position 2 
on tray 1 (near the middle of the insulated door) represents the least 
rapid temperature changes for that tray; and the curve for position 1 
on tray 8 (directly over the middle of the pan of water) represents a 
relatively slow rate of heating and cooling, combined with a period longer 
than in any other part of the chamber, during which the temperature 
was nearly constant in the neighborhood of the maximum temperature 
for that position. 
The extremes of temperature in different parts of the chamber were 
i.6° C. apart before the heating was begun, 3.2 0 when heating was dis¬ 
continued, and 4.5 0 at the end of the 7-hour period. With the discon¬ 
tinuance of rapid cooling at the end of 7 hours, of course the temperature 
in different parts of the chamber became gradually equalized so that 
the temperature curves would converge if continued beyond the 7-hour 
period. 
