It should be thoroughly understood by all that any common paper, coarse wrapping paper, new or old newspapers, etc., are admirable to keep out cold or keep in warmth. The blood of all domestic animals, as well as of human beings, must be always kept very near 98 degrees, just as much in winter as in summer. And this heat always comes from within the body, whenever the atmosphere is not above 98 degrees temperature. So long as the air is cooler than this, the heat produced inside the body is escaping. Heat seeks a level. If there is more in one of two bodies or substances side by side, the heat will pass from the warmer into the colder, until they are both of the same temperature.
Moving air carries away vastly more heat than still air. The thin film of air next to the body soon gets warm from it. But if that air is moved along, slowly or swiftly, by a breeze, be it ever so gentle, new cooler air takes its place, and abstracts more heat from the body. Anything that keeps the air next to the bodies of men and of animals from moving, checks the escape of heat.
The thinnest paper serves to keep the air quiet. A newspaper laid on a bed acts much as a coverlid to keep a film or layer of air quiet, and thus less heat escapes from the bodies of the sleepers. If paper is pasted up over the cracks of a house, or of a barn or stable, or under the joists of a house floor, it has just the same effect. Every person who keeps animals will find it a wonderful and paying protection to them, to put against the walls one, two, three, or more layers of newspapers during cold weather. If a person in riding finds his garments too cool, a newspaper placed under the coat or vest, or under or over the trousers, even if only on the side next the wind, will do a great deal to check the outflow of heat, and keep him warm. Two or three thicknesses of newspaper crumpled a little, and put under the coat or overcoat, are almost as effective in keeping in warmth as an extra garment. A slight crumpling keeps them a little separate, and makes additional thin layers of air.
Further: Heat does not pass through films of still air. Fibrous woolens, furs, loosely woven cotton, down, and the like, contain a great deal of air confined in the meshes, and are therefore excellent conservers of heat. Double walls of stone, brick, or wood, or even of wall or roofing paper, double glass, double layers of anything that will have thin layers of still air between them, prevent the escape of heat greatly.