Always breathe through the nose. Fifty years ago Mr. Catlin wrote a book called _Shut your Mouth and Save your Life_, and he showed how the Red Indians for a long time had adopted that method with their children to the extent of a cruel habit of tying up their jaws at night, to ensure breathing through the nostrils.
Breathing through the nose prevents germs of disease getting from the air into the throat and stomach; it also prevents a growth in the back of the throat called "adenoids," which reduce the breathing capacity of the nostrils, and also cause deafness.
By keeping the mouth shut you prevent yourself from getting thirsty when you are doing hard work. The habit of breathing through the nose prevents snoring. Therefore practice keeping your mouth shut and breathing through your nose.
A Scout must be able to hear well. The ears are very delicate, and once damaged are apt to become incurably deaf. No sharp or hard instrument should be used in cleaning the ear. The drum of the ear is a very delicate, tightly stretched skin which is easily damaged. Very many children have had the drums of their ears permanently injured by getting a box on the ear.
A Scout, of course, must have particularly good eye-sight; she must be able to see anything very quickly, and to see it a long way off. By practicing your eyes in looking at things at a great distance they will grow stronger. While you are young you should save your eyes as much as possible, or they will not be strong when you get older; therefore avoid reading by lamplight or in the dusk, and also sit with your back or side to the light when doing any work during the day; if you sit facing the light it strains your eyes.
The strain of the eyes is a very common failure with growing girls, although very often they do not know it, and headaches come most frequently from the eyes being strained; frowning on the part of a girl is very generally a sign that her eyes are being strained. Reading in bed brings headaches.
Bad teeth are troublesome, and are often the cause of neuralgia, indigestion, abscesses, and sleepless nights. Good teeth depend greatly on how you look after them when you are young. Attention to the first set of teeth keeps the mouth healthy for the second teeth, which begin to come when a child is seven and these will last you to the end of your life, if you keep them in order.