The ordinary oblong sink is an abomination. That great surface of stone, which is always left wet, is always exhaling into the air. I have known whole houses and hospitals smell of the sink. I have met just as strong a stream of sewer air coming up the back staircase of a grand London house from the sink, as I have ever met at Scutari; and I have seen the rooms in that house all ventilated by the open doors, and the passages all _un_ventilated by the closed windows, in order that as much of the sewer air as possible might be conducted into and retained in the bed-rooms. It is wonderful. Another great evil in house construction is carrying drains underneath the house. Such drains are never safe. All house drains should begin and end outside the walls. Many people will readily admit, as a theory, the importance of these things. But how few are there who can intelligently trace disease in their households to such causes! Is it not a fact, that when scarlet fever, measles, or small-pox appear among the children, the very first thought which occurs is, "where" the children can have "caught" the disease? And the parents immediately run over in their minds all the families with whom they may have been. They never think of looking at home for the source of the mischief. If a neighbour's child is seized with small-pox, the first question which occurs is whether it had been vaccinated. No one would undervalue vaccination; but it becomes of doubtful benefit to society when it leads people to look abroad for the source of evils which exist at home. [Sidenote: Cleanliness.] 4. Without cleanliness, within and without your house, ventilation is comparatively useless. In certain foul districts of London, poor people used to object to open their windows and doors because of the foul smells that came in. Rich people like to have their stables and dunghill near their houses. But does it ever occur to them that with many arrangements of this kind it would be safer to keep the windows shut than open? You cannot have the air of the house pure with dung-heaps under the windows. These are common all over London. And yet people are surprised that their children, brought up in large "well-aired" nurseries and bed-rooms suffer from children's epidemics. If they studied Nature's laws in the matter of children's health, they would not be so surprised.