This, of course, will depend upon the exercise he takes; but, on an average he should have every night at least eight hours. It is a mistaken notion that a boy does _better_ with _little_ sleep. Infants, children, and youths require more than those who are further advanced in years; hence old people can frequently do with little sleep. This may in a measure be accounted for from the quantity of exercise the young take. Another reason may be, the young have neither pain nor care to keep them awake: while, on the contrary, the old have frequently one or both: “Care keeps his watch on every old man’s eye, And where care lodges, sleep will never lie.” ON THE TEETH AND THE GUMS. 350. _What are the best means of keeping the teeth and the gums in a healthy state?_ I would recommend the teeth and the gums to be well brushed with warm salt and water, in the proportion of one large teaspoonful of salt to a tumbler of water. I was induced to try the above plan by the recommendation of an intelligent American writer. The salt and water should be used _every night_ at bedtime. The following is an excellent tooth-powder: Take of finely-powdered Peruvian Bark; „ Prepared Coral „ Prepared Chalk; „ Myrrh, of each half an ounce; „ Orris root, a quarter of an ounce; Mix them well together in a mortar, and preserve the powder in a wide-mouth stoppered bottle. The teeth ought to be well brushed with the above tooth-powder every morning. If the teeth be much decayed, and if, in consequence, the breath be offensive, two ounces of finely-powdered charcoal, well mixed with the above ingredients, will be found a valuable addition. Some persons clean their teeth every morning with soap; if soap be used it ought to be Castile soap, and if the teeth be not white and clear, Castile soap is an excellent cleanser of the teeth, and may be used in lieu of tooth-powder as before recommended.