Not enough attention is paid to the selection of colors for resisting the heat. Two cloths identical except in color will show a great difference in the comparative amount of heat they let through. Light shades should be chosen, but care should be taken to see that they are not glaring, so as to irritate the eye and increase the mental effect of heat. Linen and silk are better non-conductors than wool. And the weave of a cloth has a great deal to do with the amount of heat it lets through. Smooth, hard weaves absorb much less heat than fuzzy weaves. For this reason, serge is much cooler than worsted of the same shade and weight. A mistake is often made, however, in getting serge of a dark blue. It should be of as light a color as possible; gray is much cooler than blue. A white serge is much cooler than white flannel, because it is less fuzzy. Linen is much cooler than woolens, because it is a better non-conductor and is of more porous weave. The linen thread is rough, which causes inequalities in the weave, permitting a more thorough circulation of air. Cotton is a still better non-conductor than linen, and would be preferable for summer clothes but for the fact that it neither wears nor holds its shape so well. Mohair is very light in weight and cool looking. As a matter of fact, however, it is a fairly good conductor of heat, is closely woven, and usually comes in dark shades. It is a woolen cloth, and any woolen has its threads woven more closely on account of the process of manufacture than linens, cotton, and silk cloths. Linen is perhaps the best material for summer wear. It is porous in weave, light in color, and of fairly light weight. It is well to remember that the safety valve of the body in hot weather is the evaporation of perspiration, not the act of perspiring. If the hand is put in a glove, for instance, it will perspire much more than if in the open air, but it will not be as cool. It is the evaporation that is a cooling process. If the perspiration is absorbed it cannot evaporate. That is why loose fitting undergarments are cooler than tight ones. It is also the reason why cotton is cooler next to the skin than linen or silk; it absorbs moisture less freely.