The labouring man, above all others, should rise in the morning refreshed by nature’s sweet restorer—balmy sleep. But, by neglecting ventilation, it is not so. Drowsiness, sickness, headache, and languor are his lot; and in order to bring himself up to the mark, he is obliged to have recourse to artificial stimulants. Scavengers are necessary to maintain the comfort and cleanliness of our streets, so oxygen is necessary to maintain the health and comfort of our bodies. By depriving our bodies of pure air, we deprive them of the power to throw off infectious diseases. This may simply be illustrated by placing a lighted candle under a shade when a limited amount of air only can be introduced. If not supplied the candle will go on burning for a while, giving out less light and less heat; but when the oxygen is exhausted, the candle will die out. Thus it is with man. The candle, when deprived of pure air, gave evidence of less light, so to man under the same conditions would give evidence of less life. A lower vitality is equivalent to a closer approach to death. Day is opposed to night. Life to death. But even as between day and night there is twilight, so in our experience there is the twilight of disease. Thousands in this metropolis, through the neglect of the laws of health, live in the twilight of disease, rather than in the noon-day brightness of health. I have endeavoured to show that fresh air is a necessary of life just as much as food. I have indicated its importance in relation to health and how imperatively necessary it was in sickness to aid the body to overcome disease. If overcrowding in small dwellings and its consequent ill effects upon health, morality, and industry be a necessary social evil, it is evidently our duty to lessen that evil, if we cannot altogether remove it. This, in some measure, may be accomplished by free ventilation and paying due regard to the ordinary sanitary laws of health. If we turn a deaf ear to the warning voices of conscience and reason, and go on living and breaking the laws of health, we must expect to pay the penalty for breaking those laws. If men habitually sleep in an atmosphere of carbonic acid gas and fetid exhalations, they must of necessity exhaust the vitality of their bodies.