be seen by plunging the hand quickly into water, and then holding it still, when little silvery bubbles will be seen on the skin. But in other animals better covered than man, air adheres in considerable quantities to the thick hair, fur, wool, and feathers, adding to their warmth-saving capabilities, and here again wool is indicated as a most suitable-clothing material: for cotton, linen, and silk, having smoother surfaces, do not provide so protective an atmosphere.
Nature points to wool as the proper clothing of man, as of the lower animals, and, as is only to be expected under the circumstances, it fulfils all the conditions necessary for the preservation of health, as far as dress is concerned; it retains more warmth, while weighing less than any other material, and it allows the skin to perform those functions of transpiration, interference with which is the precursor of disease, while stoppage of them causes death, as surely as the cessation of breathing through the lungs, consequent on suffocation.
To speak now of the ventilating power of various materials. It might appear at first sight, and is, indeed, often maintained by the thoughtless, that the more impervious to air a material is the warmer it must be; but experience teaches us that this is not so. For instance, a kid glove, which can hardly be said to allow any air to pass through it, feels by no means so warm on the hand as one knitted out of wool, through which a great amount of air can pass, as may easily be seen by blowing through it. If we call the ventilating power of flannel 100, that
