Now this man only did what anyone else can do, that is to secure a daily supply of fresh air. There are vast numbers of people who would be different creatures if they would have a walk morning and evening, either before breakfast or their evening meal, or on their way to and from their work. [Sidenote: Fresh air in the home.] It is of little use, however, to take walks in the fresh air if we come back to badly-ventilated houses. There are some dwellings in which the air always feels dead; there is a staleness about it which offends our nostrils the moment we cross the threshold. The doors and windows are kept closed, and the whole house reeks of the accumulated poison from the lungs of those who have lived beneath its roof. In a north country dale there is a charming cottage, its latticed windows framed in creepers, standing back from the village street. It is the admiration of all beholders, yet its beauty is only the shell that hides a grim tragedy. There were five children in the family, and one by one they died of consumption. And if you examine the pretty latticed windows more closely, you will find the secret of their fell disorder, for not one of those windows, upstairs or down, will open. Those youngsters played in the fresh air, they went to school and returned home in it, but every minute that they spent in the house they were living in a poisoned atmosphere. If there had been no such thing as bedtime, they might have escaped; but it was no wonder that when some tubercle bacilli made their way into that house they found easy victims in the innocent, sleeping forms of those children. For even the fireplace in the bedroom was blocked up with a sack of shavings. An atmosphere of that sort is like a two-edged sword, it cuts both ways. It not only lowers the resisting power of the human body, but also favours the growth of germs. And consumption is not the only complaint to which vitiated air may lead. There are many other forms of ailments which, if not so deadly as this disease, exercise a most pernicious influence on health. Common colds play a far greater havoc with the health of a nation than is usually supposed. For it is not merely the loss of time spent in getting rid of them, but the infinitely more important fact that these chills and catarrhs upset digestion, lower the general health, and lay it open for deadlier enemies to enter. Sometimes colds are of the influenza nature, the result of a germ, which may fix itself in the throat in spite of all precautions. Yet the influenza bacillus itself finds the greatest ally in any catarrh of the nose or throat. We frequently hear people say that they had an ordinary cold which developed into influenza. It is a perfectly true statement, and if the ordinary cold had not been there first, it is more than probable that the influenza germ would not have had a chance of establishing itself.