The sand is first removed, and the rock is smoothed on the surface. A space about twelve feet each way is next divided into slabs one foot square, the grooves between them being cut with a light, flat-pointed, single-bladed pick. These are raised successively by a tool something between an adze and a mattock, a single stroke of which is in general sufficient for the detachment of each from its bed. The blocks thus cut out and raised being laid aside, the bed is once more smoothed, and the operation resumed, till the pit reaches the depth of six or eight feet. This variety of building material is brought in vast quantities to Bombay, where a large portion of the native houses are built of it. It is not very strong, but, with the admirable cement employed, it makes a good and economical wall.
Trap.—In the Dekhan, the most massive struc tures are raised and carved on trap with delicacy and correctness. The favourite material for the over - ground Mahomedan tombstone is basalt, and, after many hundred years, the Arabic letters, carved in relief, are as sharp as on the day they were first cut. The vaults and domes of tombs and temples are commonly bolted with iron from top to bottom ; and in many cases, instead of scaffolding, the structure is surrounded with a rough wall, ten or twenty feet off, the interval between being filled up with earth ; a long inclined plane serves for raising the stones. A magnificent structure of this sort, the tomb of one of the Gwalior princes, has stood half - finished near Poona since the early part of the 19th century, and here native architecture may be seen in per fection in all stages of advancement.
The only other building material at the Bombay Presidency consists of a fine-grained variety of nummulite, like Bath oolito, called, from the name of the place whence it comes, Porebunder stone.
All over India, bricks, laterite, and clay are largely used ; in the Mauritius, stone and slabs of coral rock. In many parts of Bengal, wattle work is in use for houses.
Since Indian railroads were commenced, with their great spanning bridges, the rocks of all their neighbourhoods have been largely utilized ; and buildings formed of the greenstones, granites, lime stones, clayslate, and sandstones are everywhere to be seen. Throughout the great volcanic district of the Dekhan, the various kinds of greenstone are largely used. On the blue slate formation, along the valleys of the Kistna and Tumbudra, and on the compact limestone formation on each side of these rivers, houses have ever been formed from these materials ; but the favourite rock for ornamental purposes in the Buddhist and Hindu temples of peninsular India, is the dark basaltic greenstone, often, from its high polish, called black marble. In an ancient underground temple at Bijapur this basalt is alone employed. The Brahmanical and Buddhist caves of Ellora and Ajunta, and the smaller caves at Mominabad, aro excavated out of the greenstone and greenstone amygdaloid. At Ellora they are about twenty in number, in the face of the mountain, almost scarped as it falls into the valley of the Godavery ; a similar number are at Ajunta, in a ravine near the scarped ghats overlooking Kandesh. Those on the right bank of the Irawadi, near Prome, look on the river. In Madras and Calcutta, and
in Indian towns generally, brick is the ordinary building material. In the whole of Burma and the Tenasserim Provinces, the houses are on posts, and built of wooden planks with shingled roofs.
Of the rocks of aqueous origin, the sandstones, slates, and limestones, the whole of the valley of the Kistna, and great parts of the valleys of its affluents, the Gutpurba, Malpurba, Bhima, Tunga, Bhudra, and Tumbudra, and much of the valley of the Godavery and of the valleys of its northern affluents, have limestone, clayslate, and sand stone rocks, and the houses and more extensive buildings are all built of these. The compact limestone of Kurnool, westward to the Bhima, is an excellent building material.
The whole of the Kymore range in Shahabad is described as of mountain limestone, which also shows itself in the valley of the river Sone as far at least as Mungeysur peak in Mirzapur ; and it crops up at Rhotas, forming a sloping base to the precipitous sandstone rock. Below the mountain limestone is one of a plush grey colour, mixed with occasional crystals of talc spar ; this, like the Kurnool stone, is admirably suited for lithography. Below the latter, in Kymore, is a limestone of a hard, tenacious, almost indestructible composition, admirably suited for building.
The sandstones of the hymore range have a high commercial value at Chunar and Mirzapur, being used as flagstones and for ornamental pur poses, the proximity of the Ganges affording an easy river carriage ; otherwise they are the worst and most destructible description of stone in the range. The millstones of Chynepore, Sasseram, and Tilowthoo (perhaps also Akbarpur), are famous, but must always bo dear iu a distant market, for want of river carriage. The Sone causeway and the Koylwan railway bridge are built of the dense sandstone of Sasseram ; little quantities are found in the higher portions of the range towards Rhotas. The best stone, while easily workable, is almost as bard as granite, and may be had of any colour, white, crystalline, blue, grey, and all shades to a dark red.
Flexible sandstone is found at Ulwar, Jhend, and Jubbulpur.
At the Panjab Exhibition held at Lahore, there was a good collection of building materials from Sahi Balabgarh in the Dehli district, including the red, the spotted, and the light-coloured sand stone so much used in the large buildings of Upper Hindustan ; and from the same place were polished blocks of white marble, and a pretty dappled grey marble, called Narnaul marble, from the Hissar district. From the Kangra district there was sent grey limestone, sandstone of two sorts, both good for building, and granite. Some nice workable sandstone sent from Madhopore must come from the hills above that place. From Kashmir there was some black marble, and some polished slabs of serpentine, which is found at Tasbgaon in Little Tibet. The Salt Range, Jhelum, and Shahpur districts possess good building stones, sandstone, and calcareous sandstone ; from Jhelum were specimens of marble which might become useful for building, with gypsum or alabaster of the same hills. See Architecture.