With the great movement throughout the country for public health, there seems little excuse for ignorance regarding fabrics that conserve health, yet the general public is ignorant or indifferent, or both, to organized effort for better conditions. Much has been said about the athletic American woman and her sensible clothes, but she is still woefully lacking from the strictly hygienic standpoint. Education, common sense, and combined effort need to be applied to the clothing problem, not to produce a sudden or peculiar dress reform, but to improve still further dress of the present day.

Machinery produces an endless variety of materials, artists create beautiful costumes, the gymnasium, the tennis court, the swimming pool develop splendid figures. Yet colds, pneumonia, and tuberculosis are too prevalent. Undoubtedly improper clothing must bear part of the blame for this.

From the arctic regions to the heart of the tropics men wear clothing of one kind or another. Sometimes this clothing is very limited, but even the string of beads of the Central African serves his purpose of dress. The clothing of the Eskimo prevents him from freezing to death; the South Sea Islander satisfies his love of decoration with the few garments he wears, and charms the tropical lady with his belt of feathers.

Throughout history dress has fulfilled one need or another. In modem civilized society it must satisfy several demands. Protection from the elements, modesty, ornament, and fashion must all have a place, and it is often difficult to provide for all of these needs in one costume. The special field of hygiene of dress is the proper protection of the body, not only from the elements, but also from the tyranny of fashion.

It is not the purpose in this chapter to discuss the large problem of proper clothing, but merely that part of it which has to do with the qualities of materials. To understand this question one must know what bodily needs clothing has to fulfill and what qualities different materials have to enable them to meet the requirements. Living conditions have changed greatly in the last few decades. Houses are warmer, street and railway cars are overheated, public buildings are often hot, and the home is not as draughty as it used to be, therefore the costume which was proper two generations ago is not suitable today. There are still, however, cold days and damp days, and outdoor conditions are much as they always have been. Modern physiological science has changed our views somewhat in regard to the needs of clothing, but has not yet thoroughly taught us just what the proper clothing should be.

For physical and mental efficiency it is necessary that the body be warm, clean, have unrestricted circulation of blood and unrestricted ability to breathe. Man, unlike other animals, is unable to live in cold climates nor can white man live in tropical climates with only his natural coverings, but must depend on clothes for protection. If protection were the only requirement of dress the problem would be fairly simple, but fashion dictates how garments must be made entirely regardless of the health of the wearer. Then the individual tries to make them meet the demands of fashion and sometimes of hygiene as well.

Clothing which comes next the skin should be of such a character that it will help maintain a constant body temperature, will absorb and take care of the perspiration, give proper ventilation to the skin, and also be of such nature that it may be cleaned readily. It is important that the body be not overheated. In modern city apartments there is much more likelihood of this than of the other extreme.

A material to be warm need not necessarily be heavy or thick. The requirements differ for an outer and an under garment. An undergarment may be loosely woven, quite light in weight, and yet be warm. Still air is a poor conductor of heat, and the air which is held in the meshes of an undergarment is warm, gives opportunity for ventilation, and aids in evaporating the perspiration. In an outer garment a loose weave gives opportunity for the wind to pass through and allows too rapid a change of air underneath, and so is not warm. Several layers of light weight material are better than one layer of thick material, because of the layers of air held between them.

The warmth of a material also depends on the conductive power of the fiber from which it is woven.

Wool and silk are poor conductors of heat, cotton and linen better conductors. Linen feels cold to the touch, and is therefore pleasant for summer clothing. The conductive power of the fibers is not, however, as great a consideration as that of the amount of air inclosed in the meshes of the fiber.

The nature of the fibers, whether they will mat closely together or remain apart because of their elasticity and inclose air, also the weave of a fabric are very important factors in determining the warmth of a garment. Wool has this elasticity and makes a warm fabric, but after frequent washing the fibers become more felted together and harder, and the material is less desirable; this is especially true when it is carelessly washed. Linen and cotton may be woven with large meshes, but are ordinarily woven into close, thin materials, which are not very warm.

Heat is carried from the body in three ways: (1) By conduction by the still air or the clothing materials. (2) By convection, moving air which takes the warm air from next the body and replaces it with cold air which must then be warmed. (3) By the evaporation of perspiration.