Geological survey and Measurements in Vaastu Shastra
The soils were to be tested on the basis of the five senses like the color, smell, sounds, touch and taste. SHILPA SHASTRA or VAASTU SHASTRA says that there are four types of soils suitable for the four predominant castes (or ‘VARNAS, which also means ‘color’).
On the basis of taste, lands are classified again into four categories as per the four castes, namely,
(i) Sweet for Brahmanas
(ii) Astringent for Kshatriyas,
(iii) Pungent for Vysyas and
(iv) Bitter for Sudras.
These classifications were only recommendatory and were not followed very strictly.
Different castes were placed in different parts of a city. The Brahmins and the astrologers were placed on the northern side, the market place and the traders were placed on the north-eastern corner, the location of the palaces and the royal personnel were on the eastern part, the south-east was occupied by the goldsmiths and the soldiers.
The southern part was resided over by the slaves and the workers. The south-western part was occupied by the shepherds, herdsman and the fishermen.
The western side was occupied by the drivers, the royal servants and the police. The municipal administrators and the merchants were settled on the north-western part of the city.
Though it seems that the location of the various castes on the various parts of the city depended on the climatological conditions and the social status of the castes, all these were given a camouflage of astrology so that the common people follow them with some sort of religious austerity.
The selection of site for the construction of buildings depended on many tests, some of which is stated here under :-
(1) To dig a hole of certain dimensions on the proposed site. Then the hole is filled up with the earth dug out for the very same hole. Now, there can be three cases; the filled earth can form a dune over the hole, it can just fill the hole, or it can dip down at the middle.
If the earth pile up in the shape of a dune, then the plot is very good for building purposes as the earth elsewhere is compact. If the earth just fills up the hole, then the soil condition is moderate and if it dips down, then the soil is unsuitable for building purposes as the earth elsewhere in the site is concluded to be loose.
(2) To dig a hole and fill the hole with water, after a night, if the water level in the hole comes down, the soil is not suitable as the soil is lose and water percolates through it, and it will hold not, enough water to sustain the population.
Measurements in Town Planning in Vaastu Shastra
A Human Scale was adopted for measurements in Vastu Shastra. The unit of scale was DANDA which is equal to the distance between the outstretched hands of a man. The other smaller units which followed were: JAV (grain of barley), ANGUL (finger), BALISHT (palm size) and HAST (hand).
Norms for selection of a building site
The soils which are to be avoided for building purposes are:
(a) Those soils which are full of ashes, charcoal, skulls, bones, husks of corn, hairs, poison, stones or which are full of rats, anthills and gravels.
(b) Lands which are hollow, dry, zig-zag in shape, having decayed wood, subterranean pits, barren, having water current moving to the left, devoid of rains, where trees are bitter, thorny, useless, devoid of fruits, abounding in birds eating raw flesh or where worms are found.
(c) Land which is sharp and dry, too hot or too cold to touch, are to be rejected. if the soil is bitter, or salty to taste, it should be avoided. Lands, when struck, that generate the sound of a jackal, camel, dog or donkey or the torrent of a crude sound like that of a breaking jar is to be avoided.
Hence the stability and the fertility of the soil is tested and ensured. Also mineral resources were tapped and building materials were explored. Land by the side of a river has a problem of floods and the proclivity of the ground is important.
Shilpa Shastra says that if the ground is slanting towards the directions presided over by Varuna, Varna, Marut, Agni or if it is depressed in the middle, it is to be avoided.
House having a low ground on the left and raised on the right is beset of many ills. Similarly if it is low on right and raised on the left it is also unfit. Further, hollowness and low ground on the back is also bad. Only the ground with west-ward slops and frontal projection is the fittest one.
In NAGAR RACHANA SHASTRA (YUKTI KALPATARU), Bhoja says that the osound should be elevated in the middle, and slanting towards east and north-east.
Practically, all the shilpa shastras are unanimous in extolling an easterly declination of the ground it offers full benefit of the morning sun.
Town planning in medieval India was probably the concern of the State, as such a wide range of perspective directions could not have been within easy reach of individual resources. Town Planning, then, was a social function.