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. The number of blankets needed depends somewhat upon the time of year and the locality of use and whether or not the all night fire is to be used. In ordinary summer weather one blanket is enough especially if combined with the proper browse bag and wind break and is enough even for frosty autumn temperatures up to stream freezing time, excepting in the higher altitudes. With the temperature under thirty-two degrees two Army blankets will be needed. Many mountaineers to whom strenuous pedestrianism and cold nights of the higher altitudes necessitate the lightest form of bedding prefer wool quilts which are folded and sewed on one end and half up one side in the form of a sleeping bag which is protected from the damp ground by a waterproof balloon silk cover. Where the transportation is inadequate as on a hike trip, the wearing of an extra suit of underwear is as warm as an extra blanket. One then gets the dead air space between the wool and the warmth is thereby intensified because the number of layers of covering retains the heat longer than one thick layer of the same weight.