sleeping-place perfectly dry and comfortable; he should not cease until
he is convinced that it will withstand the chill of the early morning,
when the heat of the yesterday's sun is exhausted, and that of the coming
sun has not begun to be felt. It is wretched beyond expression for a man
to lie shivering beneath a scanty covering and to feel the night air
become hourly more raw, while his life-blood has less power to withstand
it; and to think, self-reproachfully, how different would have been his
situation if he had simply had forethought and energy enough to cut and
draw twice the quantity of firewood, and to spend an extra half-hour in
labouring to make himself a snugger berth. The omission once made becomes
irreparable; for in the cold of a pitiless night he has hardly sufficient
stamina to rise and face the weather, and the darkness makes him unable
to cope with his difficulties.

Bivouac in Special Localities.--Encampment in Forests.--A clump of trees
yields wonderful shelter. The Swedes have a proverb that "the forest is
the poor man's jacket." In fir-woods there is great facility in making
warm encampments; for a young tree, when it is felled, yields both poles
to support branches for shields against weather, and finer cuttings for
flooring above the snow or damp. A common plan is to support a cross-bar
by two uprights, as shown in the figure; against this cross-bar a number
of poles are made to lean; on the back of the poles abundance of fir
branches are laid horizontally; and lastly, on the back of these are
another set of leaning poles, in order to secure them by their weight.

[Sketch of pole shelter].
On Bare Plains.--Avoid sleeping in slight hollows during clear still
weather. The cold stratum of air, of which I spoke in the section of
"Shelter from the Sky," pours down into them, like water from the
surrounding plain, and stagnates. Spring frosts are always more severely
felt in hollows. Therefore, in a broad level plain, especially if the
night be clear and calm, look out for some slightly rising ground for an
encampment. The chilled stratum of air drains from off it, and is
replaced by warmer air. Horses and cattle, as the night sets in, always
draw up to these higher grounds, which rise like islands through the sea
of mist that covers the plain.

Walls have been built for shelter against the wind, on a bare sandy
plain, by taking empty bags, filling them with sand, and then building
them up as if th