12 EXTRACTING AND CLEANING FOREST TREE SEED. 
DISTRIBUTION OF HEAT. 
One of the most difficult problems in running an improvised kiln 
is to maintain a constant supply of heat and distribute it evenly 
through all parts of the drying room. The first step should be to 
make the room, whether in a building or tent, as tight as possible, 
except for the vents required for ventilation. AlIl chinks in a build- 
ing should be closed completely. The next precaution is to secure 
as constant temperature as possible. Wherever practicable, as hot 
a fire should be kept up at night as during the day. This is particu- 
larly necessary in a tent, where any dying down of the fire at night 
causes the air to cool rapidly, with consequent delay and loss of time 
and labor. 
| The stove has ordinarily been placed in the center of the room 
and approximately level with the lowest tiers of trays. This results 
in much slower drying of the cones near the bottom of the room 
and at a distance from the stove. Attempts have been made to 
obviate this difficulty by dividing the stovepipe into sections and 
carrying it through as much of the room as possible, but without 
complete success. Better drying is secured in the farther ends of 
the room, but the bottom remains much cooler than the top. This 
difference is especially marked in tents, where cold air constantly 
passes in under thé walls. With only one stove, even distribution 
of heat is impossible. With stoves set at opposite ends of the tent 
and connected by a single stovepipe, conditions are but little better. 
In one instance where this arrangement was used, a difference of 
from 20° to 30° F. was found in the temperature of the air at the © 
highest and lowest trays in a six-tier stack 
One method of hastening the opening of the cones in the lower 
trays is to raise them as the drying proceeds and the cones in the 
upper trays are removed. This, however, requires additional hand- 
ling and loss of time. A better method wherever space is available 
is to place the lowest tier of trays somewhat above the stove. Room 
for air circulation is essential. The tiers of trays should be at least 
6 inches apart vertically, preferably 8 inches, and the same distance 
from the walls. f 
Heating the dry room from below.—The best method of securing 
even distribution of heat, although not always practicable, is to have 
the drying room heated from below. If conditions permit, excavate 
under the building and place the stove below the floor. This will 
not only heat the room above more evenly, but furnishes additional 
space for spreading cones. The stovepipes should pass through as 
many parts of the dry room as possible. Still better results will be 
obtained if hot-air pipes can be conducted from the drum of the 
stove into the room above, and even more heat can be made available 
