Where circumstances will permit a choice, towns should be built in wholesome situations and dry soils; and the same holds with additions making to old towns. The health of a community is much influenced by the situation in which they live, and by the nature of the ground on which their houses are built. In many towns there are some particular districts in which disease is more particularly prevalent, and the result of careful inquiry is, that the excessive disease is owing to unwholesomeness of situation. Persons in all other respects similarly situated, enjoy a better state of health, or suffer less disease, who inhabit a more wholesome or less prejudicial situation or locality. SEWERS. A point next in importance to a proper construction of streets, and the selection of good situations, is an efficient system of drains or sewers for the removal of impurities, and the formation of water-courses. Of the importance of sewers it is unnecessary to enlarge, that being sufficiently understood. By water-courses is meant channels for the immediate passage of rainwater from off the streets. They are easily formed, and where the ground is level, the advantage is very great. In streets having a slope or declivity, the water is soon dispersed; but where they are level, it is apt to collect, and there create dampness, which is communicated to the houses, and a favourable nidus for putrefaction, where impurities are permitted to accumulate. In some parts, principally the suburbs of large towns, and in many of the villages of Scotland, perhaps more especially those along the coasts, inhabited by fishermen, no means being adopted to expedite the removal of rainwater, and there being no natural water-run or course, the rain collects, and animal and vegetable materials mixing therewith, green putrefying ditches are formed, plentifully evolving gaseous products, and supporting a luxuriant vegetation on their surface. CONSTRUCTION OF HOUSES. So much attention is now paid to health and comfort in the construction of the houses of the wealthy, that it is unnecessary to say a word respecting these points, in connection with the higher classes. But the circumstances being so very different in relation to the houses of the poor or the labouring class, some notice is required here. It too often happens that the house of the labouring man in the country is, in almost every respect, little better than a shed, and calculated to produce disease. The walls are frequently the only substantial part of the tenement, the roof of tiles being often pervious to the rain and wind, and there being no other covering either of lath or lime; the door opens directly into the body of the house, and the floor is generally either below or on a level with the ground outside. When floors of houses are below the level of the ground outside, they must necessarily be damp, and cause the house to be unwholesome.