Mathematics in Ancient and Medieval India c6.s2.10

c6.s2.10

The *Śulbasūtras* have made use of the east-west line for the purpose of all constructions, and drawing works namely the construction of sacrificial altars. Haug has given at the end of his *Aitareya Brāhmaṇa*³ a tolerably good map of the sacrificial compound of which the central line is an east-west line. In Vedas also, the measurements of the altars are given with reference to this central east-west line. The *Āhavanīya* fire is ordained by a Vedic text to be directly to the east of the *Garhapatya* fire. The fire *Dakṣiṇāgni* is to the south of this central east-west line. The *Pāśuki*-vedi for the Paśubandha sacrifice, a *Sautrāmaṇi* vedi which is called the *Mahāvedi* for the Somasacrifice; in all these vedis, the central east-west line remains fixed. In a *Saptapuruṣa*- *cayana*, for example, say, *Śyena-cayana* (bird-shaped construction), the whole figure is symmetrical with respect to the central east-west line. Its wings and tail are symmetrically arranged. It is in fact the most important line and the whole sacrificial theatre, is symmetrical with respect to this central line. The central east-west line was called *pṛṣṭhyā* or *prācī*. In the construction of the altars in the *Śulbasūtras* the tern *prācī* was in fact a line of specific length drawn parallel to or on this central east-west line and which was drawn in such a way that the figure concerned must be symmetrical which the *prācī*.