For keeping the dampness absorbed by the walls from affecting the air of the house, a Portland cement coating may be perhaps the best means now available. It would have been much better, when the walls were first built, to brush the outside of them with melted coal tar; but that is probably impracticable now. If the earth stands against the walls, however, the cement coating should cover the whole inside of the wall. The situation of the building may perhaps admit of draining away the water which accumulates about it, by means of stone drains or lines of drain tile, laid up to the cellar walls, at a point below the basement floor, and carried to a convenient outfall. This would be the most desirable of all methods for drying the cellar, and should be first tried.
Construction for Earthquake Countries.—The conditions will vary somewhat according to the nature of the climate.
R. H. Brunton, who was for many years resident lighthouse engineer in Japan, follows the principles enunciated by Mallet and Prof. Palmieri, giving the buildings weight and great inertia, coupled with a good bond between their various parts. Prof. Palmieri states that, although solidity and strength in a building do not afford perfect protection, still, so long as fracture does not occur, overthrow is impossible. Dyer states that in his opinion, for dwelling-houses in Japan, the modifications of external design required, as compared with those in Britain, arise not so much on account of the earthquakes as from the heats of summer, the colds of winter, and the typhoons of autumn. Iron roofs are good from a merely structural point of view; but in summer it would be impossible to live in the houses provided with them. If a non-conducting material of the same strength and durability as iron could be found, it might be used. “If the houses are so designed as to be comfortable as regards temperature, and the construction made in good brick, or equally strong stone and mortar, so that the walls are of nearly a uniform strength; if no unnecessary top weights are used, and if the various parts do not vibrate with different periods, they will withstand all ordinary earthquakes, and other precautions will be unnecessary, as these generally produce results more serious than those due to the earthquakes.”
The city of Arequipa, Peru, is particularly liable to earthquakes, owing to its proximity to the great volcano, the Misti, 19,000 ft. in height above sea-level, the city being 7000 ft. above sea-level. The general construction of the houses is peculiar. A light coloured volcanic stone is largely used; this, when quarried, is easily shaped, and it hardens gradually. The roofs are for the most part strong arches, a very good mortar being used. In the earthquake of 1868, it was not so much those arches which failed as the walls, and the spandrels between the arches at front and rear. In some parts of the city, arches extending in one direction stood, while those at right angles to these were thrown down. Since 1868, a good many corrugated iron roofs have been introduced; but they are not suitable to the climate, and are not durable.
Earnshaw, from an experience of 25 years in Manila, where the earthquakes are sometimes very severe, comes to the conclusion to build as strongly as possible, and chiefly in wood, tied and bolted together as in a ship, stone and brickwork only being used in the lower story and in the foundations, and especial attention ought to be paid to the quality of the lime and mortar used in construction. Many materials have been used as roofing, such as the heavy tiles made in the country and others imported there. When, in 1880, fully 60 per cent. of the buildings in Manila had been ruined, an order was issued by the municipal authorities to use corrugated iron or zinc sheeting for that purpose. A diversity of opinion existed as to which was the best and most suitable, for not only had earthquakes to be guarded against, but intense heat and disastrous typhoons. With reference to the latter, in 1881, sheets of iron were flying about in the air like paper. He thinks, therefore, that a light, strong tile roofing is preferable to any other.
Prof. C. Clericetti, of Milan, and W. H. Thelwall relate that after the earthquake in the island of Ischia in 1883, which was of a most destructive character, and caused an enormous amount of damage in the island, 2000 persons having lost their lives, and many more being injured, a commission was appointed by the Italian Government to obtain information, and to frame rules for the rebuilding of the structures. It was ascertained that, speaking generally, buildings founded on hard, solid lava had withstood the shock successfully, whilst those founded upon looser or lighter materials, such as tufa or clay, had suffered very much, and therefore in regard to the re-erection of buildings it was pointed out that the first thing to do was to select eligible sites, and to build, wherever possible, upon lava; and, where that was not possible, to dig down to comparatively solid ground, and then fill in a heavy platform of masonry or concrete, 3 ft. or 4 ft. thick, extending over the whole area of the building, and projecting 3 ft. or 4 ft. beyond. The building of any kind of vaulting above ground was forbidden. Light arches were only to be allowed over window’s and openings of that kind. The heavy flat roofs formerly used to a large extent were condemned. The commission recommended that buildings should be chiefly constructed with an iron or wooden framework, carefully put together, joined by diagonal ties, horizontally and vertically, with spaces between the framework filled in with masonry of a light character. The joists and the roof trusses were to be firmly connected together. In plan, buildings should be square, and where the direction of the last shock could be traced, one diagonal should be placed in this direction. Not more than two stories above ground were to be allowed, and there might be one under ground, but it must be of very moderate height. In no case was the height from the lowest point of the ground to the top of the walls to exceed 31 ft. Openings for doors and windows were to be vertically over each other, the jambs being not less than 5 ft. from the corner of the building. No openings for flues were allowed in the thickness of the walls, and no projections from the face of a building, except light balconies of wood or iron. If solidly built structures, and particularly if there was only one story above ground, the roofs might be covered with tiles; but these must be light, and fastened with nails or hooks, so as not to be displaced even by violent shocks.
Water Supply and Purification
Water Supply and Purification.—The supply of water to both town and country houses has been dealt with at length by Eassie and Rogers Field in essays written for the Health Exhibition Handbooks, and the following information is mainly condensed and adapted from their papers.
The conditions of supply in the two cases differ in being from a general and public source in the one and from a special and private source in the other. In each case, the consumer has to control the purity and application of the supply after its delivery into the dwelling; and in the second case he is further responsible for the character and quantity of the supply before delivery. The second case, therefore, in a great measure covers the first, and demands extended treatment.
Amount required.—The first consideration is the quantity of water required. The supply to towns from waterworks is usually expressed in “gallons per head of population per diem,” and varies exceedingly, much of the variation being due to waste. This is especially the case in towns where the supply is intermittent. In several towns having a constant supply, steps have been taken systematically to measure the water supplied to different streets and districts, and it has been found that, without restricting the supply in any way, the consumption of water has been immensely reduced, simply by sending inspectors to make a house-to-house visitation and search out and repair leaky pipes and defective taps and ball-cocks. It is by no means an unusual thing for the consumption to be reduced one-half by inspections of this kind, showing that at least one-half of the water which was previously supplied to the houses was simply wasted through leaky fittings.