This section is from the "A Complete Dictionary of Dry Goods" book, by George S. Cole. Also available from Amazon: A complete dictionary of dry goods and history of silk, cotton, linen, wool and other fibrous substances,: Including a full explanation of the modern processes ... together with various useful tables.
Underwear. Underclothing; under linen; a general term which includes every article worn beneath the external or outer garments, by day or by night, both of men and women. Undetwear is made of every conceivable sort of material, as silk, cotton, wool, linen, stockinette, spun silk, lace, cambric, merino, flannel, nainsook, elastic, jean, muslin, etc. There has been much dispute among the advocates of the various fibers as to •which was the most suitable for underwear. Wool has been recommended by eminent medical authorities for both hot and cold countries on account of its property of promoting insensible perspiration, which being absorbed by the spongy material is immediately distributed equally throughout the whole thickness of the fabric; and thus being exposed over a large surface is carried off by the atmosphere, keeping the body at the same time at an equal temperature. Wool, relatively to linen and cotton (it is claimed) is a non-conductor of heat and electricity, and therefore tends to preserve to the body its normal measure of these vital energies. It is the function of the skin through its 7,000,000 pores to throw off from 28 to 32 ounces of exhalations (refuse matter) which is generated in the body during every 24 hours. All kinds of animal wool and hair readily absorb the excretions of the skin, but does not retain them, but transmit, and disperse them at their outer surfaces by a repulsive energy to which the self-cleansing properties of hair and wool are properly due. The value of this feature of the woolen system is very apparent. Silk is also recommended for underwear, and possesses several advantages over other fibers. The fiber of silk is perfectly smooth, symmetrical and solid, not hollow like cotton and linen fibers, and without the minute scales peculiar to wool. Silk is a great absorbent because its fibers are so glassy fine —a sort of spidery catgut - and fluids, water or perspiration creep between the fibers and are held, yet will pass out quickly, evaporating and drying, or will wash out readily. It is like glass, in that nothing clings to it. In its natural color silk accumulates no germs of disease and moths and bugs find no home in it. For these reasons when made up into underwear, it is necessarily hygienic and salutary. Linen is advocated as a superior material for underwear on account of its absorbent qualities. The majority of the peasants of Russia wear linen next to the skin and claim that it is as warm as wool, and in addition that it wears longer, is more easily washed, does not shrink, and sheds dust and dirt much more readily. [See Kneipp Linen]
It may be laid down as a rule that during a greater portion of the year in northern climates undergarments of heavy material should be worn by persons exposed to the weather. However, it is unnecessary and unwise for individuals following indoor occupations to wear the heavier varieties of underwear. The person who changes his gauze for the heaviest flannel on September 15, and continues these heavy garments until May 15, regardless of the varions changes in the weather, may be as much in error as he who wears gauze only the year around. A clerk who is in a warm room the greater part of the day is not expected to wear the same weight of underwear as a teamster or street car driver, who is out of doors and much exposed. In short, one's underwear should depend upon the degree of his exposure, and should be of a weight that will insure the greatest comfort during that part of the day when he is at his particular occupation; and if more warmth is required when not at work it should come from additional outer clothing.