important, therefore, that wells should never be sunk in the vicinity of cesspools or similar anti-hygienic contrivances.
In towns and villages where the water supply is doubtful, during epidemics of typhoid or cholera, all water used for drinking purposes should be boiled and filtered through some reliable make of filter. It must, however, be borne in mind that filtration only removes substances mechanically suspended in the water; to free the liquid thoroughly from all dissolved matter boiling or distillation is requisite. A well-constructed filter, especially one in which sand is the medium, will practically remove all the bacteria. Generally speaking, a filter should be cleansed once a month in summer, and every two months in winter.
When travelling in unhealthy countries, or during the prevalence of an epidemic, it is a wise plan to use for cooking or drinking purposes only boiled rain-water, if obtainable. The small portable filters such as those which were supplied to our soldiers in South Africa are invaluable travelling companions in a malarial district, in an emergency when reliable water cannot be had.
Make it a rule neither to sleep nor eat in a house where the drains are in bad order.
Baths and Bathing.—The employment of baths goes back to the highest antiquity, and was indulged in almost to excess by the Greeks and Romans. So important are baths in warm countries, that the Jewish and Oriental religions enjoin frequent ablutions as a necessary part of the ceremonials of their creeds; this no doubt has largely contributed to the health and well-being of their adherents.
In order to understand the value of bathing we must glance briefly at the anatomy and physiology of the skin. In the first place, we have on the entire outer surface of the body a layer of membrane, like thin leather, called the epidermis or cuticle; this stratum is not supplied with nerves, and is therefore insensitive. It is the portion which rises up when the hands are blistered by rowing, or when a fly blister is applied.
Just beneath the epidermis lies the true skin, or corium, a tough strong membrane, richly supplied with blood vessels and nerves. Hence it bleeds and feels pain at the slightest cut or puncture, since even the finest needle cannot be thrust into it without wounding some little artery or vein and some tiny filament of nerve. Under the true skin again lies the subcutaneous cellular tissue, which generally contains a quantity of fat.
The most important constituents of the skin to be noticed for our present inquiry, are first, the sweat glands; second, the oil glands; and third, the hair and nails are usually spoken of as appendages to the skin.
The sweat glands are twisted and coiled-up tubes, occupying the true skin and the layer of tissue beneath. They open upon pores,