districts where they occur. Being destitute of car bonate of lime or magnesia, or containing them only in very minute quantities, they are not exposed to the corroding action of the acids which pervade the air. There is, indeed, a remarkable suitability in the distribution of building stones in Great Britain to the especial wants of different parts of the country. Thus amongst the mining and manufacturing districts of the centre of Scotland, and the north and centre of England, siliceous sandstones are plentifully de veloped in the Carboniferous and Triassic formations; while the soft calcareous stones of the Jurassic (or Oolitic) series are distributed amongst the compara tively smokeless districts of the south and east, where the purity of the atmosphere, and a less watery sky, admit of a lengthened duration for buildings constructed of such materials. Whilst the principles here laid down are applicable to all climates and all lands, there is one observation which must be constantly borne in mind, and without which the application of general principles would be of no avail, that without due care in the selection of the stone in the quarry, there can be no security for the excellence of the material. It is to the absence of this precaution, that the failure in many portions of the exposed surface of the New Houses of Parliament is generally attri-