Location of dwelling - houses.—— The inhabitants of malarious districts ought to live in villages or towns with well-paved streets and courts, going out to cultivate their fields during the day, but returning to sleep in the town before nightfall. Houses should be placed, if possible, on high and dry situations, a clay soil being avoided. All forest under-growth should be cleared away. It is unwise in countries such as Africa, where nearly all Europeans suffer from chronic malarial poisoning, to place dwelling-houses in exposed situations, or where high winds are apt to produce chills and consequent fever relapses. For the same reason, in elevated situations houses should be well sheltered by trees planted at some distance from the premises, or by higher ground. In the neighbourhood of houses the felting of natural grass should, if possible, be preserved, or, if it be disturbed, replaced immediately, or the exposed soil covered with rammed clay or cement. It is unwise to have flower-beds or vegetable gardens near bedroom windows, or to allow water from bath-rooms or cook-houses to flow over the ground in the vicinity of the house, or to keep water unchanged in tubs or water-butts for mosquitoes to breed in. Pools and puddles of stagnant water should be filled up and turfed. Water-butts and cisterns should be screened, and sagging roof-gutters rectified; discarded tins, jars, pots, bottles, and all rubbish capable of holding water in which mosquitoes could breed should be got rid of, and plants or trees in which collections of water occur should be cut down. Ponds should be stocked with fish, as fish tend to keep down mosquitoes by preying on their larvæ. The neighbourhood of swamps is to be avoided. A few ounces of petroleum thrown on the surface of a pond will prevent mosquitoes from depositing their eggs on the water, and will asphyxiate their larvæ; the petroleum requires to be renewed from time to time—— say once a week. Coal tar may be used in the same way. There are many simple precautions of this sort which will occur to every prudent man, and which, in malarious countries, he should take care to have carried out.
