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.