In all likelihood you will depend for warmth upon blankets. Their use is so universal that we need no discussion other than in regard to their quality and shape. As commonly used a blanket bed throws open easily; there is no condensation of moisture and the sleeper is able to wrap up snugly, retaining all of the generated animal heat. Lambs’ wool fibers are peculiar in that they have a natural repulsion for water. They have the attribute of holding air in the interstices between the fibers, thus creating a dead air space which is a nonconductor of heat. On account of these things wool becomes ideal for body covering. Damp wool will not chill, which condition the outer is often up against many times a day. In summer the evaporation of surplus moisture and in winter the retention of animal heat is obtained. The thicker and looser the texture of woolen goods the greater will be the warmth.
Cotton is objectionable because it is not warm and is in danger of being “fired” from stray camp fire sparks. The wool of the South American llama is a new material used for outing purposes and besides having all the good attributes of lamb’s wool has an additional one of being very much lighter in weight. A llama blanket weighs about six pounds and equals in warmth about fifteen pounds of ordinary blanket. The secret of its warmth is in the great number of air cells between the loose texture of its fibers which retain body heat. At the same time it gets rid of the moisture which the sleeper throws off in great quantities as natural body emanations. Its prohibitive cost will prevent its general adoption.
Eiderdown in no way equalizes temperatures. It simply retains moisture and heat and is too warm except on the coldest nights. Usually in the form of a quilt whose outer cloth covering tears easily the fluffy down is hard to control. It is of little use beneath the sleeper because the pressure squeezes out the confined air.
The blanket as well as the union suit then had best be all wool of the domestic lamb variety. In buying blankets beware that many of those offered you may be humbug. See to it that you get an article made up of curly wool fibers and not “adulterated” by the straight cotton kind--a differentiation easily determined by the aid of a small magnifying glass. Also see to it that the weight is in the thickness and not in the size. In this country the regulation Army blanket is to be depended upon. However, if they can be secured, a person will certainly make no mistake in getting a genuine Hudson Bay or Mackinaw. The proper weight is about five pounds per blanket and size seventy-two by seventy-eight is about right. If you get it too narrow you cannot then roll it up so snugly for packing nor wrap it so closely about the body at night.