THE ARCTIC 
139 
least a small crack where the door is covered by a block of snow, 
ice, or other object. Otherwise those inside might suffocate. 
Such a shelter, if properly made, will hold several people comfort- 
ably. The Eskimos make a more elaborate snow-block house, 
but this calls for considerable skill and the method of construc- 
tion should be learned from the natives themselves. 
In timbered country it is easy to make a comfortable shelter 
in the form of the lean-to described for the tropics (p. 64). 
Only instead of coconut or similar leaves you will have spruce 
boughs. Cover the three sides of the framework with overlap- 
ping rows of flat spruce boughs, beginning at the bottom and laid 
with their tips downward. Place several layers of spruce boughs 
inside the shelter to form a floor. Have the open side of the 
shelter face the fire and away from the prevailing wind. 
If timber is not available a wall of snow* can be made for a 
windbreak. If a tent is used in open country it should not be 
placed under a cliff or in the lee of any large sheltering object, 
for snow may drift down and bury it. It will be well, however, 
to build a snow wall on the windward side to protect the tent 
from wind and drifting snow. If the wall is built close to the 
tent there will be no danger from snow drifts. 
In pitching the tent the snow should be removed from the 
inside and replaced by a layer of grass, moss, or boughs to 
prevent the sleeping bags or other bedding from becoming wet. 
Where the snow is deep it can be stamped down to make a firm 
floor which can be covered with boughs or whatever materials 
are available. Sleeping bags should not rest against the tent 
walls. 
CARBON MONOXIDE POISONING 
If a tent or other closed shelter is used, it must be carefully 
ventilated. A fire of any kind burning in a closed and poorly 
ventilated space may produce carbon monoxide, a deadly poison- 
